Abstract

Trace concentrations of 1,4-dinitrobenzene (DNB) are detected by a combination of laser photolysis and laser-induced fluorescence. A one-color laser is applied to induce DNB photodissociation and for subsequent detection of NO photofragments by excitation and emission through A(v′ = 0) ← X(v″ = 0 - 2) and A(v′ = 0) → X(v″ = 0, 1) transitions, respectively. The resulting NO rovibrational excitation spectra serve as markers for the presence of DNB. The NO is produced in vibrational ground and excited states with peak height ratios of (v″ = 0):(v″ = 1):(v″ = 2) = 1:0.5:0.13. The limits of detection of DNB mixed with 100 or 500 Torr of air with v″ = 2 excitation at 248 nm are 13 and 11 parts in 10⁹ by weight, respectively, for a 30-s integration time. The application of this scheme for DNB detection has the advantage that no ambient ground state NO interferes and that the fluorescence is collected at shorter wavelengths than the exciting radiation, precluding background fluorescence.

© 1999 Optical Society of America

Photodissociation followed by laser-induced fluorescence at atmospheric pressure and 24 °C: a unique scheme for remote detection of explosives

Talya Arusi-Parpar, Dov Heflinger, and Raphael Lavi
Appl. Opt. 40(36) 6677-6681 (2001)

Laser photofragmentation–fragment detection and pyrolysis–laser-induced fluorescence studies on energetic materials

Vaidhianat Swayambunathan, Gurbax Singh, and Rosario C. Sausa
Appl. Opt. 38(30) 6447-6454 (1999)

Detection of condensed-phase explosives via laser-induced vaporization, photodissociation, and resonant excitation

C. M. Wynn, S. Palmacci, R. R. Kunz, K. Clow, and M. Rothschild
Appl. Opt. 47(31) 5767-5776 (2008)

Spectral differentiation of trace concentrations of NO₂ from NO by laser photofragmentation with fragment ionization at 226 and 452 nm: quantitative analysis of NO–NO₂ mixtures

Robert L. Pastel and Rosario C. Sausa
Appl. Opt. 39(15) 2487-2495 (2000)

Disturbance of laser-induced-fluorescence measurements of NO in methane–air flames containing chlorinated species by photochemical effects induced by 225-nm-laser excitation

Pascale Desgroux, Pascal Devynck, Laurent Gasnot, Jean-François Pauwels, and Louis-René Sochet
Appl. Opt. 37(21) 4951-4962 (1998)