K. M. Evenson, Trevor J. Sears, and A. R. W. McKellar, "Far-infrared laser magnetic resonance of vibrationally excited CD2," J. Opt. Soc. Am. B 1, 15-21 (1984)
We report the detection of 13 rotational transitions in the first excited bending state (010) of CD2 using the technique of far-infrared laser magnetic resonance spectroscopy. Molecular parameters for this state are determined from these new data together with existing infrared observations of the ν2 band. Additional information on the ground vibrational state (000) is also provided by the observation of a new rotational transition, and this is combined with existing data to provide a refined set of molecular parameters for the CD2 ground state. One spectrum has been observed that we assign as a rotational transition within the first excited symmetric stretching state (100) of CD2. These data will be of use in refining the structure and the potential function of the methylene radical.
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Sources for the laser wave-number references may be found in Ref. 20.
Transitions are within the (010) excited vibrational state except where otherwise indicated.
Transitions in the ground vibrational state of CD2 have previously been observed with these laser lines (see Ref. 11).
Table 2
Observed Resonant Fields and Assignments of LMR Transitions in the (010) Excited Vibrational State of CD2
See Table 1.
1 T = 104 G.
The assignment given for J is that with which the given MJ level correlates at zero field.
Calculated tuning rate in megahertz/gauss.
These transitions were given a reduced weight in the least-squares fit (0.1) because of weakness and/or blending.
Table 3
Observed Resonant Fields for the 523–514 Transition in the (000) Ground Vibrational State of CD2 Observed with a 13CH3OH Laser Line at 90.55315 cm−1
From, a fit to the previous11 far-infrared LMR data with the addition of the measurements of the 523 ← 514 transition given in Table 3.
From a fit to ν2-band diode-laser measurements12 and the data of Table 2. For both states, magnetic g values were fixed at theoretical values,21,22 and the numbers in parentheses are one standard deviation from the least-squares fit expressed in units of the last quoted digit.
Fixed at a value determined from the energy levels given by Bunker and Jensen.13
Fixed at the ground-state value.
This parameter and all others not listed were fixed at zero.
Table 5
Observed Resonant Fields for the 322 ← 211 Transition in the (100) Excited Vibrational State of CD2 Observed with a 13CH3OH Laser Line at 117.209532 cm−1
Observed Field (T)
Assignment
J′ ← J″
MJ′ ← MJ″
0.0135
4 ← 3
2 ← 2
0.0151
4 ← 3
1 ← 1
0.0183
4 ← 3
0 ← 0
0.0256
4 ← 3
−1 ← −1
0.0286
3 ← 3
2 ← 2
0.0519
4 ← 3
−2 ← −2
0.0575
4 ← 1
−1 ← −1
0.1219
4 ← 1
0 ← 0
0.0129
4 ← 3
0 ← 1
0.0156
4 ← 3
−1 ← 0
0.0181
4 ← 3
2 ← 1
0.0216
4 ← 3
1 ← 0
4 ← 3
−2 ← −1
0.0249
4 ← 3
3 ← 2
0.0299
4 ← 3
0 ← −1
0.0423
4 ← 3
−3 ← −2
0.0554
4 ← 1
−2 ← −1
0.0607
4 ← 1
0 ← −1
0.0635
4 ← 3
−1 ← −2
0.1322
4 ← 1
1 ← 0
Table 6
Comparison of Experimental Fine-Structure Parameters for Isotopic Forms of Methylene (in inverse centimeters)
Sources for the laser wave-number references may be found in Ref. 20.
Transitions are within the (010) excited vibrational state except where otherwise indicated.
Transitions in the ground vibrational state of CD2 have previously been observed with these laser lines (see Ref. 11).
Table 2
Observed Resonant Fields and Assignments of LMR Transitions in the (010) Excited Vibrational State of CD2
See Table 1.
1 T = 104 G.
The assignment given for J is that with which the given MJ level correlates at zero field.
Calculated tuning rate in megahertz/gauss.
These transitions were given a reduced weight in the least-squares fit (0.1) because of weakness and/or blending.
Table 3
Observed Resonant Fields for the 523–514 Transition in the (000) Ground Vibrational State of CD2 Observed with a 13CH3OH Laser Line at 90.55315 cm−1
From, a fit to the previous11 far-infrared LMR data with the addition of the measurements of the 523 ← 514 transition given in Table 3.
From a fit to ν2-band diode-laser measurements12 and the data of Table 2. For both states, magnetic g values were fixed at theoretical values,21,22 and the numbers in parentheses are one standard deviation from the least-squares fit expressed in units of the last quoted digit.
Fixed at a value determined from the energy levels given by Bunker and Jensen.13
Fixed at the ground-state value.
This parameter and all others not listed were fixed at zero.
Table 5
Observed Resonant Fields for the 322 ← 211 Transition in the (100) Excited Vibrational State of CD2 Observed with a 13CH3OH Laser Line at 117.209532 cm−1
Observed Field (T)
Assignment
J′ ← J″
MJ′ ← MJ″
0.0135
4 ← 3
2 ← 2
0.0151
4 ← 3
1 ← 1
0.0183
4 ← 3
0 ← 0
0.0256
4 ← 3
−1 ← −1
0.0286
3 ← 3
2 ← 2
0.0519
4 ← 3
−2 ← −2
0.0575
4 ← 1
−1 ← −1
0.1219
4 ← 1
0 ← 0
0.0129
4 ← 3
0 ← 1
0.0156
4 ← 3
−1 ← 0
0.0181
4 ← 3
2 ← 1
0.0216
4 ← 3
1 ← 0
4 ← 3
−2 ← −1
0.0249
4 ← 3
3 ← 2
0.0299
4 ← 3
0 ← −1
0.0423
4 ← 3
−3 ← −2
0.0554
4 ← 1
−2 ← −1
0.0607
4 ← 1
0 ← −1
0.0635
4 ← 3
−1 ← −2
0.1322
4 ← 1
1 ← 0
Table 6
Comparison of Experimental Fine-Structure Parameters for Isotopic Forms of Methylene (in inverse centimeters)