OSA's Digital Library

Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 1 — Jan. 14, 2013
  • pp: 918–926
« Show journal navigation

Scanning near-field optical coherent anti-Stokes Raman microscopy (SNOM-CARS) with femtosecond laser pulses in vibrational and electronic resonance

Mahesh Namboodiri, Tahir Zeb Khan, Sidhant Bom, Günter Flachenecker, and Arnulf Materny  »View Author Affiliations


Optics Express, Vol. 21, Issue 1, pp. 918-926 (2013)
http://dx.doi.org/10.1364/OE.21.000918


View Full Text Article

Acrobat PDF (4539 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

Accessing ultrafast photoinduced molecular dynamics on a femtosecond time-scale with vibrational selectivity and at the same time sub-diffraction limited spatial resolution would help to gain important information about ultrafast processes in nanostructures. While nonlinear Raman techniques have been used to obtain highly resolved images in combination with near-field microscopy, the use of femtosecond laser pulses in electronic resonance still constitutes a big challenge. Here, we present our first results on coherent anti-Stokes Raman scattering (fs-CARS) with femtosecond laser pulses detected in the near-field using scanning near-field optical microscopy (SNOM). We demonstrate that highly spatially resolved images can be obtained from poly(3-hexylthiophene) (P3HT) nano-structures where the fs-CARS process was in resonance with the P3HT absorption and with characteristic P3HT vibrational modes without destruction of the samples. Sub-diffraction limited lateral resolution is achieved. Especially the height resolution clearly surpasses that obtained with standard microCARS. These results will be the basis for future investigations of mode-selective dynamics in the near field.

© 2013 OSA

1. Introduction

The investigation of the influence of the nano-structuring of materials on the ultrafast photo-induced dynamics is of considerable interest. An important example is the charge carrier formation dynamics in organic solar cells [1

1. P. G. Nicholson and F. A. Castro, “Organic photovoltaics: principles and techniques for nanometre scale characterization,” Nanotechnol. 21, 492001 (2010). [CrossRef]

]. Here, bulk heterojunctions of donor and acceptor molecules, such as poly(3-hexylthiophene) (P3HT) as p–type and [6,]-phenyl C61 butyric acid methyl ester (PCBM) as n–type semiconductor, play a big role [2

2. K. Yonezawa, M. Ito, H. Kamioka, T. Yasuda, L. Han, and Y. Moritomo, “Carrier formation dynamics of organic photovoltaics as investigated by time-resolved spectroscopy,” Adv. Opt. Tech.Doi [CrossRef] (2012).

]. The surface morphology of this system has been investigated by Kilmov et al.[3

3. E. Kilmov, X. L. W. Yang, G. G. Hoffmann, and J. Loos, “Scanning near-field and confocal Raman microscopic investigation of P3HT–PCBM systems for solar cell applications,” Macromolecules 39, 4493–4496 (2006). [CrossRef]

] using scanning near-field optical microscopy (SNOM) Raman measurements.

In order to investigate the structure dependence of the exciton dynamics, a combination of an initial femtosecond pump excitation followed by a time-delayed femtosecond coherent anti-Stokes Raman scattering (fs-CARS) event would present a powerful tool. Tuning the laser wavelengths to an electronic transition resonance helps to select a specific electronic state and making use of the Raman resonance will yield mode-specific dynamics, which is strongly influenced by structural properties of the system and its environment [4

4. T. Siebert, R. Maksimenka, A. Materny, V. Engel, W. Kiefer, and M. Schmitt, “The role of specific normal modes during non-Born-Oppenheimer dynamics: the S1-S0 internal conversion of β-carotene interrogated on a femtosecond time-scale with coherent anti-Stokes Raman scattering,” J. Raman Spectrosc. 33, 844–854 (2002). [CrossRef]

, 5

5. V. Namboodiri, A. Scaria, M. Namboodiri, and A. Materny, “Investigation of molecular dynamics in β-carotene using femtosecond pump-FWM spectroscopy,” Laser Phys. 19, 154–161 (2009). [CrossRef]

]. For nano-systems, a high spatial resolution is very important. CARS microscopy has emerged as a well-known nonlinear microscopy technique for imaging chemical and biological samples. The non-invasive, chemical specificity inherent to the contrast originating from vibrations of the nuclei and high signal strength due to the coherent nonlinear interaction make this technique special compared to other existing microscope techniques. Duncan et al.[6

6. M. Duncan, J. Reintjes, and T. J. Manuccia, “Scanning coherent anti-Stokes Raman microscope,” Opt. Lett. 7, 350–352 (1982). [CrossRef] [PubMed]

] first constructed a CARS microscope by employing a non-collinear geometry. The molecular specificity inherent to this technique was demonstrated by differentiating in a CARS image a two immiscible liquid mixture (octane and acetonitrile) contained in an optical cell. The images were recorded by scanning the interface between the two liquids. In the CARS process, the frequency difference between the pump pulse (ωp) and Stokes pulse (ωS) is tuned to be in resonance with a vibrational (Raman) mode of the molecule (ωpωS = ΩR). The coherent excitation of the vibrations makes the third probe pulse (ωpr) to scatter at the anti Stokes frequency (ωaS) such that, ωaS = ωpωS +ωpr, following the conservation of energy. In a degenerate pump probe CARS, the pump itself acts as the probe (ωp = ωpr), giving the CARS signal at ωaS = 2ωpωS. Zumbusch et al.[7

7. A. Zumbusch, G. R. Holtom, and X. S. Xie, “Three-dimensional vibrational imaging by coherent anti-Stokes Raman scattering,” Phys. Ref. Lett. 82, 4142–4145 (1999). [CrossRef]

] improved the CARS microscope by employing collinear geometry and tight focusing of the laser beams using high NA objectives. This could improve the spatial resolution compared to the non-collinear configuration by (Duncan et al.). The tight focusing helps to reduce the lack of signal generation due to phase mismatch. The main problem affecting the contrast of the CARS images is the unwanted non-resonant background signal from e.g. solvent molecules or the non-vibrational contributions from the analyte itself. A lot of developments have been made in terms of improving image contrast (suppressing the non resonant background) and faster imaging [8

8. C. L. Evans and X. S. Xie, “Coherent anti-Stokes Raman scattering microscopy: chemical imaging for biology and medicine,” Annu. Rev. Anal. Chem. 1, 883–909 (2008). [CrossRef]

]. The modern CARS microscope can record images in vivo at video rate speed [9

9. C. L. Evans, E. O. Potma, M. Puorishaag, D. Cote, C. P. Lin, and X. S. Xie, “Chemical imaging of tissue in vivo with video-rate coherent anti-Stokes Raman scattering microscopy,” Proc. Natl. Acad. Sci. USA 102, 16807–16812 (2005). [CrossRef] [PubMed]

]. A possible way to minimize the non-resonant background is the use of a time delay between the laser pulses in a femtosecond CARS experiment due to the short life time of the non-resonant contributions [10

10. A. Volkmer, L. D. Book, and X. S. Xie, “Time-resolved coherent anti-Stokes Raman scattering microscopy: imaging based on Raman free induction decay,” Appl. Phys. Lett. 80, 1505–1507 (2002). [CrossRef]

].

The spatial resolution of an optical microscope is limited by the diffraction limit (0.61 × λ/NA). SNOM techniques [11

11. E. Betzig and J. K. Trautman, “Near-field optics: Microscopy, spectroscopy, and surface modification beyond the diffraction limit,” Science 257, 189–195 (1992). [CrossRef] [PubMed]

, 12

12. E. Betzig, P. L. Finn, and J. S. Weiner, “Combined shear force and near-field scanning optical microscopy,” Appl. Phys. Lett. 60, 2484–2487 (1992). [CrossRef]

] can be combined with microscopy to improve the spatial resolution for spectroscopy [13

13. M. Lucas and E. Riedo, “Combining scanning probe microscopy with optical spectroscopy for applications in biology and materials science,” Rev. Sci. Instrum. 83, 0611011 (2012). [CrossRef]

, 14

14. L. Novotny and J. S. Stranick, “Near-field optical microscopy and spectroscopy with pointed probes,” Annu. Rev. Phys. Chem. 57, 303–331 (2006). [CrossRef] [PubMed]

]. The combination of SNOM for recording signals induced by ultrafast laser pulses yields better image resolution and allows for local probing of ultrafast dynamics confined to a nanometer scale. Hess et al.[15

15. H. F. Hess, E. Betzig, T. D. Harris, L. N. Pfeiffer, and K. W. West, “Near-field spectroscopy of the quantum constituents of a luminescent system,” Science 264, 1740–1745 (1994). [CrossRef] [PubMed]

] have shown that spatial averaging of spectral information is reduced by local detection using SNOM. The SNOM techniques can be categorized into two subgroups, (i) one using tips with an aperture and (ii) one using aperture-less tips. In aperture SNOM, a tip with an aperture diameter smaller than the excitation wavelength(s) is employed to collect the signal or as a point source for excitation in the near field [16

16. B. Hecht, B. Sick, U. P. Wild, V. Deckert, R. Zenobi, O. J. F. Martin, and D. W. Pohl, “Scanning near-field optical microscopy with aperture probes: fundamentals and applications,” J. Chem. Phys. 112, 7761–7774 (2000). [CrossRef]

]. The latter is not applicable with femtosecond pulses because of the chirp-induced temporal and intensity-induced spectral broadening effects. Aperture SNOM has been widely used for high resolution imaging applications that are based on the collection of fluorescence and photoluminescence. Recently, we have demonstrated that a femtosecond pump-probe experiment (transient absorption) in combination with the SNOM technique can be applied for chemical specific imaging along with probing the local dynamics [17

17. K. Karki, M. Namboodiri, T. Z. Khan, and A. Materny, “Pump-probe scanning near-field optical microscopy: sub-wavelength resolution chemical imaging and ultrafast local dynamics,” Appl. Phys. Lett. 100, 1531031 (2012). [CrossRef]

]. In the apertureless type, a metallic nano particle attached to the tip is used to enhance the signal produced in the near field. Tip-enhanced Raman is a well known technique and applied in imaging and single molecule detection schemes are being developed in this field [18

18. V. Deckert, “Tip-enhanced Raman spectroscopy,” J. Raman Spectrosc. 40, 1336–1337 (2009). [CrossRef]

, 19

19. R. C. Dunn, “Near-field scanning optical microscopy,” Chem. Rev. 99, 2891–2927 (1999). [CrossRef]

]. Publications presenting examples for a combination of CARS and SNOM techniques are very limited. Schaller et al.[20

20. R. D. Schaller, J. Ziegelbauer, L. F. Lee, L. H. Haber, and R. J. Sayakally, “Chemically selective imaging of sub-cellular structure in human hepatocytes with coherent anti-Stokes Raman scattering (CARS) near-field scanning optical microscopy (NSOM),” J. Phys. Chem. B 106, 8489–8492 (2002). [CrossRef]

] combined aperture SNOM techniques to improve the spatial resolution of CARS images. In this experiment the phase-matching condition, which is already relaxed when using high NA objectives, is not playing a role anymore due to the near-field detection under which interferences do not occur. Kawata and co-workers [21

21. T. Ichimura, N. Hayazawa, M. Hashimoto, Y. Inouye, and S. Kawata, “Subnanometric near-field Raman investigation in the vicinity of a metallic nanostructure,” Phys. Rev. Lett. 92, 2208011 (2004).

, 22

22. K. Furusawa, N. Hayazawa, F. C. Catalan, T. Okamoto, and S. Kawata, “Tip-enhanced broadband CARS spectroscopy and imaging using a photonic crystal fiber based broadband light source,” J. Raman Spectrosc . 43, 656–661 (2012). [CrossRef]

] employed tips with metallic nanoparticle to enhance the CARS signal and could obtain CARS images with a high spatial resolution. However, these implementations of tip-enhanced CARS in the near field were restricted to the use of long laser pulses (picoseconds) with excitation far from electronic resonances.

In order to allow for high temporal resolution femtosecond laser pulses have to be used. When electronic state specificity is required (as in most time-resolved experiments), resonance with an absorption or transient absorption transition is mandatory. Both ultrashort pulses and excitation resonant with molecular absorptions is making CARS microscopy and even more near-field CARS microscopy a very demanding task, since samples can be easily destroyed. Here, we demonstrate that fs–CARS with both electronic and vibrational resonance is capable of yielding highly resolve images of P3HT in different environments. This is the first step towards experiments (like pump–CARS) accessing ultrafast mode-specific dynamics of nano-systems. It has to be pointed out, that the goal of our work was not to improve existing CARS imaging techniques, but rather to make an important step towards a time-resolved application in the near field. Better spatial resolution could be obtained under tight-focusing conditions using lasers in the near infrared spectral region and with picosecond duration along with reduced damage of the sample. However, this would not meet our requirements.

2. Experimental

The scheme of the experimental setup is given in Fig. 1. The 150 fs (775 nm, 1 kHz repetition rate, 1 mJ energy/pulse) pulses from the regeneratively amplified Ti:Sapphire laser (CPA 2010, Clark MXR) are used to pump two optical parametric amplifiers (TOPAS, Light Conversion). One of the OPAs serves as source for the pump pulses and the other one yields the Stokes pulse for the CARS experiment. Pump and Stokes pulses are compressed to ≈ 100 fs using prism pair set-ups. The timing of the individual pulses was controlled using computer-controlled delay stages in a Michelson interferometer like set-up. Moreover, the pulses were aligned collinearly and coupled into an inverted microscope (Olympus) equipped with a commercial scanning probe microscope (SPM) system (Nanonics Multiview 2000). The sample was placed on a piezo-controlled XYZ translator. The pulses were focused on to the sample with an objective lens (Olympus PLAN N 10×, NA = 0.25). The far-field CARS signal was collected by a similar objective in the forward direction. After filtering out the pump and Stokes frequencies using a short-pass edge filter (Semrock, SP01-633RS), the signal was detected by an avalanche photodiode (STM1DAPD10, Amplification Technologies, Inc). Noise and background signals were reduced using a boxcar amplifier. The sample was scanned and simultaneously the intensity was recorded at different (x,y) positions. The near-field CARS signal was collected by a SNOM tip attached to a tuning fork (Nanonics design). The signal was guided through a multi mode fiber to the detector and recorded by the avalanche photo-diode after filtering out the pump and Stokes pulse using the short pass filter. Commercially available (Nanonics) cantilevered optical fiber SNOM tips coated with thin films of Cr and Au with an aperture diameter of less then approx. 300 nm were used in the experiments. The height of the tip above the sample was kept constant using a phase feed-back mechanism [23

23. B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, and L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys. 81, 2492–2498 (1997). [CrossRef]

]. Thus, the fiber could also be used to obtain AFM topographies from the sample with a spatial resolution limited by the fiber tip diameter. 128 × 128 pixels images were recorded with 50–100 ms integration time per pixel.

Fig. 1 Experimental scheme of the SNOM-CARS and microCARS experiments. The lasers are focused from the bottom and the transmitted signal is collected in the forward direction with an objective (far-field microCARS) or SNOM tip (near-field SNOM-CARS).

For the experiments, small structures of P3HT were prepared. Solutions in chlorobenzene contained P3HT (regio regularity greater than 98.5%, from Rieke Metals Inc.) at a concentration of 16 mg/ml. These solutions were stirred for 3–4 hours at an elevated temperature of about 60°C. About 25 mm × 25 mm microscopic slides were cut and cleaned thoroughly (first with acetone and then with isopropanol) and dried with a nitrogen gun. A solution of 500 μl was used for spin-coating on the cleaned glass substrate at 2000 rotation per minute (rpm) for 30 seconds. This resulted in an average film thickness of ≈ 100 nm. Afterwards, thermal annealing was performed at 100°C for 1 minute. The thus obtained surface had a considerable roughness and inhomogeneity in crystallinity, which is also known from the former Raman studies [3

3. E. Kilmov, X. L. W. Yang, G. G. Hoffmann, and J. Loos, “Scanning near-field and confocal Raman microscopic investigation of P3HT–PCBM systems for solar cell applications,” Macromolecules 39, 4493–4496 (2006). [CrossRef]

].

3. Results and discussion

Fig. 2 MicroCARS image (a), SNOM-CARS image (b), AFM topography (c) and CARS intensity profile (d), along a section parallel to the x direction of the images (3 × 3 μm2 area) are displayed. The color code has been adapted to the full intensity range of the image. The structure seen on the right side of the AFM image has a thickness of ≈ 145 nm.
Fig. 3 MicroCARS image (a), SNOM-CARS image (b), AFM topography (c) and CARS intensity profile (d), along a section parallel to the x direction of the images (20 × 20 μm2 area) are displayed. The color code has been adapted to the full intensity range of the image. The roughness feature on the right side of the AFM has a thickness of ≈ 1.5 μm.

The variation in intensities near the edge of the nano-structure is due to the thickness variation. The thicker the P3HT structure, the more oscillators are included in the probe volume giving rise to the CARS signal. In order to compare the variation of CARS intensity with respect to thickness, we found a region in another sample where the height of the P3HT structure is ≈ 1.5 μm. Figure 3, shows the near-field image (b) and the corresponding AFM topography (c) of this structure. The area away from the thick region corresponds to glass (SiO2), which neither contributes to the resonant CARS nor gives rise to a big non-resonant background signal, which also demonstrates our chemical selectivity and good suppression of nonresonant background signals. It can be seen that both far-field (a) and the near-field image (b) correlate with the AFM topography, with the SNOM-CARS image having a better lateral resolution. As the structure is rather thick, relative intensity changes are seen in both far-field and near-field images. When the thickness is down to a nanometer scale like in the first sample discussed above (compare Fig. 2), the far-field field intensity is almost flat and SNOM-CARS can differentiate the topographic feature much better than the microCARS. Since the SNOM probe only collects light in the near field, the SNOM–CARS does not only provide a very good lateral resolution, but clearly surpasses microCARS (also when high NA objectives are used where the lateral resolution becomes rather good). Using the axial resolution formula 1.5 × λ × n/NA2[30

30. R. H. Webb, “Confocal optical microscopy,” Rep. Prog. Phys 59, 427–471 (1996). [CrossRef]

], the maximum resolution is 742 nm for a wavelength of λ = 650 nm and a refractive index of n = 1.6 [31

31. S. V. Kamat, S. H. Tamboli, V. Puri, R. K. Puri, J. B. Yadava, and O. S. Joo, “Optical and electrical properties of polythiophene thin films: effect of post deposition heating,” J. Optelectron. Adv. M. 12, 2301–2305 (2010).

] for high NA (1.4) objectives (even much more for the objective with NA = 0.25 used in our work), and the SNOM CARS data clearly surpass this value.

The cross correlation between the pump and Stokes pulses are shown in Fig. 4. The full width at half maximum (≈ 150 fs) is equal for the near-field and the far-field experiments, showing that the temporal resolution (instrument response function) is not influenced by the SNOM tip. This is not self-evident and has to do with the fact that the pulses used in our experiments are not showing a considerable spatial chirp, which otherwise would result in different contributions at each point of the focal area.

Fig. 4 In order to estimate the temporal resolution of the CARS interaction, the cross correlation between the femtosecond pump and Stokes pulses has been measured using the microCARS and the SNOM-CARS setup. The full width at half maximum (≈ 150 fs) of the near-field and the far-field cross correlation traces reflects the respective instrument response functions, which are equal for microCARS and SNOM-CARS.

4. Conclusion

In conclusion, we have demonstrated that a femtosecond time-resolved CARS experiment is feasible with sub-diffraction limited spatial precision in both vibrational and electronic resonance without destruction of the investigated sample. Nano-structures of poly(3-hexylthiophene) (P3HT) have been imaged with molecular specificity due to electronic resonance with the transition from the P3HT ground state to its excitonic S1 state as well as vibrational resonance with the characteristic C=C ring-stretching mode of this molecule. Besides a sub-diffraction limited lateral resolution an extremely good height resolution results from the near-field optical probing. The fs-SNOM-CARS images are compared to fs-microCARS data obtained in the far field as well as the AFM topography, which is automatically obtained during the SNOM-CARS scan. The ultrashort CARS interaction will facilitate time-resolved experiments where the CARS process probes the dynamics with vibrational mode selectivity. The high temporal resolution allows for the suppression of non-resonant background signal. For future investigations we have started to use fs-SNOM-CARS in a pump-CARS experiment where exciton relaxation dynamics are probed in the near field.

Acknowledgments

Financial support by the German Research Foundation DFG ( MA 1564/17-1) is gratefully acknowledged. The authors thank Prof. Veit Wagner and Dr. Torsten Balster for access to their laboratories and help with the sample preparation.

References and links

1.

P. G. Nicholson and F. A. Castro, “Organic photovoltaics: principles and techniques for nanometre scale characterization,” Nanotechnol. 21, 492001 (2010). [CrossRef]

2.

K. Yonezawa, M. Ito, H. Kamioka, T. Yasuda, L. Han, and Y. Moritomo, “Carrier formation dynamics of organic photovoltaics as investigated by time-resolved spectroscopy,” Adv. Opt. Tech.Doi [CrossRef] (2012).

3.

E. Kilmov, X. L. W. Yang, G. G. Hoffmann, and J. Loos, “Scanning near-field and confocal Raman microscopic investigation of P3HT–PCBM systems for solar cell applications,” Macromolecules 39, 4493–4496 (2006). [CrossRef]

4.

T. Siebert, R. Maksimenka, A. Materny, V. Engel, W. Kiefer, and M. Schmitt, “The role of specific normal modes during non-Born-Oppenheimer dynamics: the S1-S0 internal conversion of β-carotene interrogated on a femtosecond time-scale with coherent anti-Stokes Raman scattering,” J. Raman Spectrosc. 33, 844–854 (2002). [CrossRef]

5.

V. Namboodiri, A. Scaria, M. Namboodiri, and A. Materny, “Investigation of molecular dynamics in β-carotene using femtosecond pump-FWM spectroscopy,” Laser Phys. 19, 154–161 (2009). [CrossRef]

6.

M. Duncan, J. Reintjes, and T. J. Manuccia, “Scanning coherent anti-Stokes Raman microscope,” Opt. Lett. 7, 350–352 (1982). [CrossRef] [PubMed]

7.

A. Zumbusch, G. R. Holtom, and X. S. Xie, “Three-dimensional vibrational imaging by coherent anti-Stokes Raman scattering,” Phys. Ref. Lett. 82, 4142–4145 (1999). [CrossRef]

8.

C. L. Evans and X. S. Xie, “Coherent anti-Stokes Raman scattering microscopy: chemical imaging for biology and medicine,” Annu. Rev. Anal. Chem. 1, 883–909 (2008). [CrossRef]

9.

C. L. Evans, E. O. Potma, M. Puorishaag, D. Cote, C. P. Lin, and X. S. Xie, “Chemical imaging of tissue in vivo with video-rate coherent anti-Stokes Raman scattering microscopy,” Proc. Natl. Acad. Sci. USA 102, 16807–16812 (2005). [CrossRef] [PubMed]

10.

A. Volkmer, L. D. Book, and X. S. Xie, “Time-resolved coherent anti-Stokes Raman scattering microscopy: imaging based on Raman free induction decay,” Appl. Phys. Lett. 80, 1505–1507 (2002). [CrossRef]

11.

E. Betzig and J. K. Trautman, “Near-field optics: Microscopy, spectroscopy, and surface modification beyond the diffraction limit,” Science 257, 189–195 (1992). [CrossRef] [PubMed]

12.

E. Betzig, P. L. Finn, and J. S. Weiner, “Combined shear force and near-field scanning optical microscopy,” Appl. Phys. Lett. 60, 2484–2487 (1992). [CrossRef]

13.

M. Lucas and E. Riedo, “Combining scanning probe microscopy with optical spectroscopy for applications in biology and materials science,” Rev. Sci. Instrum. 83, 0611011 (2012). [CrossRef]

14.

L. Novotny and J. S. Stranick, “Near-field optical microscopy and spectroscopy with pointed probes,” Annu. Rev. Phys. Chem. 57, 303–331 (2006). [CrossRef] [PubMed]

15.

H. F. Hess, E. Betzig, T. D. Harris, L. N. Pfeiffer, and K. W. West, “Near-field spectroscopy of the quantum constituents of a luminescent system,” Science 264, 1740–1745 (1994). [CrossRef] [PubMed]

16.

B. Hecht, B. Sick, U. P. Wild, V. Deckert, R. Zenobi, O. J. F. Martin, and D. W. Pohl, “Scanning near-field optical microscopy with aperture probes: fundamentals and applications,” J. Chem. Phys. 112, 7761–7774 (2000). [CrossRef]

17.

K. Karki, M. Namboodiri, T. Z. Khan, and A. Materny, “Pump-probe scanning near-field optical microscopy: sub-wavelength resolution chemical imaging and ultrafast local dynamics,” Appl. Phys. Lett. 100, 1531031 (2012). [CrossRef]

18.

V. Deckert, “Tip-enhanced Raman spectroscopy,” J. Raman Spectrosc. 40, 1336–1337 (2009). [CrossRef]

19.

R. C. Dunn, “Near-field scanning optical microscopy,” Chem. Rev. 99, 2891–2927 (1999). [CrossRef]

20.

R. D. Schaller, J. Ziegelbauer, L. F. Lee, L. H. Haber, and R. J. Sayakally, “Chemically selective imaging of sub-cellular structure in human hepatocytes with coherent anti-Stokes Raman scattering (CARS) near-field scanning optical microscopy (NSOM),” J. Phys. Chem. B 106, 8489–8492 (2002). [CrossRef]

21.

T. Ichimura, N. Hayazawa, M. Hashimoto, Y. Inouye, and S. Kawata, “Subnanometric near-field Raman investigation in the vicinity of a metallic nanostructure,” Phys. Rev. Lett. 92, 2208011 (2004).

22.

K. Furusawa, N. Hayazawa, F. C. Catalan, T. Okamoto, and S. Kawata, “Tip-enhanced broadband CARS spectroscopy and imaging using a photonic crystal fiber based broadband light source,” J. Raman Spectrosc . 43, 656–661 (2012). [CrossRef]

23.

B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, and L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys. 81, 2492–2498 (1997). [CrossRef]

24.

I. Horcas, R. Fernandez, J. M. Gomez-Rodriguez, J. Colchero, J. Gomez-Herrero, and A. M. Baro, “WSXM: a software for scanning probe microscopy and a tool for nanotechnology,” Rev. Sci. Instrum. 78, 0137051 (2007). [CrossRef]

25.

S. Falke, P. Eravuchira, A. Materny, and C. Lienau, “Raman spectroscopic identification of fullerene inclusions in polymer/fullerene blends,” J. Raman Spectrosc. 42, 1897–1900 (2011). [CrossRef]

26.

X. Feng and X. Wang, “Thermophysical properties of free-standing micrometer-thick poly(3-hexylthiophene) films,” Thin Solid Films 519, 5700–5705 (2011). [CrossRef]

27.

S. Cook, A. Furube, and R. Katoh, “Analysis of the excited states of regioregular polythiophene P3HT,” Energy Environ. Sci. 1, 294–299 (2008). [CrossRef]

28.

Y. Fu, H. Wang, R. Shi, and J. X. Cheng, “Characterization of photodamage in coherent anti-Stokes Raman scattering microscopy,” Opt. Express 14, 3942–3951 (2006). [CrossRef] [PubMed]

29.

L. Chen, H. Zhiwei, L. Fake, Z. Wei, W. H. Dietmar, and S. Colin, “Near-field effects on coherent anti-Stokes Raman scattering microscopy imaging,” Opt. Express 15, 4118–4131 (2007). [CrossRef]

30.

R. H. Webb, “Confocal optical microscopy,” Rep. Prog. Phys 59, 427–471 (1996). [CrossRef]

31.

S. V. Kamat, S. H. Tamboli, V. Puri, R. K. Puri, J. B. Yadava, and O. S. Joo, “Optical and electrical properties of polythiophene thin films: effect of post deposition heating,” J. Optelectron. Adv. M. 12, 2301–2305 (2010).

OCIS Codes
(300.6420) Spectroscopy : Spectroscopy, nonlinear
(300.6500) Spectroscopy : Spectroscopy, time-resolved
(310.0310) Thin films : Thin films
(180.4243) Microscopy : Near-field microscopy

ToC Category:
Microscopy

History
Original Manuscript: October 9, 2012
Revised Manuscript: December 6, 2012
Manuscript Accepted: December 14, 2012
Published: January 9, 2013

Virtual Issues
Vol. 8, Iss. 2 Virtual Journal for Biomedical Optics

Citation
Mahesh Namboodiri, Tahir Zeb Khan, Sidhant Bom, Günter Flachenecker, and Arnulf Materny, "Scanning near-field optical coherent anti-Stokes Raman microscopy (SNOM-CARS) with femtosecond laser pulses in vibrational and electronic resonance," Opt. Express 21, 918-926 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-1-918


Sort:  Author  |  Year  |  Journal  |  Reset  

References

  1. P. G. Nicholson and F. A. Castro, “Organic photovoltaics: principles and techniques for nanometre scale characterization,” Nanotechnol.21, 492001 (2010). [CrossRef]
  2. K. Yonezawa, M. Ito, H. Kamioka, T. Yasuda, L. Han, and Y. Moritomo, “Carrier formation dynamics of organic photovoltaics as investigated by time-resolved spectroscopy,” Adv. Opt. Tech.Doi (2012). [CrossRef]
  3. E. Kilmov, X. L. W. Yang, G. G. Hoffmann, and J. Loos, “Scanning near-field and confocal Raman microscopic investigation of P3HT–PCBM systems for solar cell applications,” Macromolecules39, 4493–4496 (2006). [CrossRef]
  4. T. Siebert, R. Maksimenka, A. Materny, V. Engel, W. Kiefer, and M. Schmitt, “The role of specific normal modes during non-Born-Oppenheimer dynamics: the S1-S0 internal conversion of β-carotene interrogated on a femtosecond time-scale with coherent anti-Stokes Raman scattering,” J. Raman Spectrosc.33, 844–854 (2002). [CrossRef]
  5. V. Namboodiri, A. Scaria, M. Namboodiri, and A. Materny, “Investigation of molecular dynamics in β-carotene using femtosecond pump-FWM spectroscopy,” Laser Phys.19, 154–161 (2009). [CrossRef]
  6. M. Duncan, J. Reintjes, and T. J. Manuccia, “Scanning coherent anti-Stokes Raman microscope,” Opt. Lett.7, 350–352 (1982). [CrossRef] [PubMed]
  7. A. Zumbusch, G. R. Holtom, and X. S. Xie, “Three-dimensional vibrational imaging by coherent anti-Stokes Raman scattering,” Phys. Ref. Lett.82, 4142–4145 (1999). [CrossRef]
  8. C. L. Evans and X. S. Xie, “Coherent anti-Stokes Raman scattering microscopy: chemical imaging for biology and medicine,” Annu. Rev. Anal. Chem.1, 883–909 (2008). [CrossRef]
  9. C. L. Evans, E. O. Potma, M. Puorishaag, D. Cote, C. P. Lin, and X. S. Xie, “Chemical imaging of tissue in vivo with video-rate coherent anti-Stokes Raman scattering microscopy,” Proc. Natl. Acad. Sci. USA102, 16807–16812 (2005). [CrossRef] [PubMed]
  10. A. Volkmer, L. D. Book, and X. S. Xie, “Time-resolved coherent anti-Stokes Raman scattering microscopy: imaging based on Raman free induction decay,” Appl. Phys. Lett.80, 1505–1507 (2002). [CrossRef]
  11. E. Betzig and J. K. Trautman, “Near-field optics: Microscopy, spectroscopy, and surface modification beyond the diffraction limit,” Science257, 189–195 (1992). [CrossRef] [PubMed]
  12. E. Betzig, P. L. Finn, and J. S. Weiner, “Combined shear force and near-field scanning optical microscopy,” Appl. Phys. Lett.60, 2484–2487 (1992). [CrossRef]
  13. M. Lucas and E. Riedo, “Combining scanning probe microscopy with optical spectroscopy for applications in biology and materials science,” Rev. Sci. Instrum.83, 0611011 (2012). [CrossRef]
  14. L. Novotny and J. S. Stranick, “Near-field optical microscopy and spectroscopy with pointed probes,” Annu. Rev. Phys. Chem.57, 303–331 (2006). [CrossRef] [PubMed]
  15. H. F. Hess, E. Betzig, T. D. Harris, L. N. Pfeiffer, and K. W. West, “Near-field spectroscopy of the quantum constituents of a luminescent system,” Science264, 1740–1745 (1994). [CrossRef] [PubMed]
  16. B. Hecht, B. Sick, U. P. Wild, V. Deckert, R. Zenobi, O. J. F. Martin, and D. W. Pohl, “Scanning near-field optical microscopy with aperture probes: fundamentals and applications,” J. Chem. Phys.112, 7761–7774 (2000). [CrossRef]
  17. K. Karki, M. Namboodiri, T. Z. Khan, and A. Materny, “Pump-probe scanning near-field optical microscopy: sub-wavelength resolution chemical imaging and ultrafast local dynamics,” Appl. Phys. Lett.100, 1531031 (2012). [CrossRef]
  18. V. Deckert, “Tip-enhanced Raman spectroscopy,” J. Raman Spectrosc.40, 1336–1337 (2009). [CrossRef]
  19. R. C. Dunn, “Near-field scanning optical microscopy,” Chem. Rev.99, 2891–2927 (1999). [CrossRef]
  20. R. D. Schaller, J. Ziegelbauer, L. F. Lee, L. H. Haber, and R. J. Sayakally, “Chemically selective imaging of sub-cellular structure in human hepatocytes with coherent anti-Stokes Raman scattering (CARS) near-field scanning optical microscopy (NSOM),” J. Phys. Chem. B106, 8489–8492 (2002). [CrossRef]
  21. T. Ichimura, N. Hayazawa, M. Hashimoto, Y. Inouye, and S. Kawata, “Subnanometric near-field Raman investigation in the vicinity of a metallic nanostructure,” Phys. Rev. Lett.92, 2208011 (2004).
  22. K. Furusawa, N. Hayazawa, F. C. Catalan, T. Okamoto, and S. Kawata, “Tip-enhanced broadband CARS spectroscopy and imaging using a photonic crystal fiber based broadband light source,” J. Raman Spectrosc. 43, 656–661 (2012). [CrossRef]
  23. B. Hecht, H. Bielefeldt, Y. Inouye, D. W. Pohl, and L. Novotny, “Facts and artifacts in near-field optical microscopy,” J. Appl. Phys.81, 2492–2498 (1997). [CrossRef]
  24. I. Horcas, R. Fernandez, J. M. Gomez-Rodriguez, J. Colchero, J. Gomez-Herrero, and A. M. Baro, “WSXM: a software for scanning probe microscopy and a tool for nanotechnology,” Rev. Sci. Instrum.78, 0137051 (2007). [CrossRef]
  25. S. Falke, P. Eravuchira, A. Materny, and C. Lienau, “Raman spectroscopic identification of fullerene inclusions in polymer/fullerene blends,” J. Raman Spectrosc.42, 1897–1900 (2011). [CrossRef]
  26. X. Feng and X. Wang, “Thermophysical properties of free-standing micrometer-thick poly(3-hexylthiophene) films,” Thin Solid Films519, 5700–5705 (2011). [CrossRef]
  27. S. Cook, A. Furube, and R. Katoh, “Analysis of the excited states of regioregular polythiophene P3HT,” Energy Environ. Sci.1, 294–299 (2008). [CrossRef]
  28. Y. Fu, H. Wang, R. Shi, and J. X. Cheng, “Characterization of photodamage in coherent anti-Stokes Raman scattering microscopy,” Opt. Express14, 3942–3951 (2006). [CrossRef] [PubMed]
  29. L. Chen, H. Zhiwei, L. Fake, Z. Wei, W. H. Dietmar, and S. Colin, “Near-field effects on coherent anti-Stokes Raman scattering microscopy imaging,” Opt. Express15, 4118–4131 (2007). [CrossRef]
  30. R. H. Webb, “Confocal optical microscopy,” Rep. Prog. Phys59, 427–471 (1996). [CrossRef]
  31. S. V. Kamat, S. H. Tamboli, V. Puri, R. K. Puri, J. B. Yadava, and O. S. Joo, “Optical and electrical properties of polythiophene thin films: effect of post deposition heating,” J. Optelectron. Adv. M.12, 2301–2305 (2010).

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

Figures

Fig. 1 Fig. 2 Fig. 3
 
Fig. 4
 

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited