Analysis of the ν12 Band of Ethylene-13C2 by High-Resolution FTIR Spectroscopy

The ν12 band of ethylene-1-13C (13C12CH4) by high-resolution FTIR spectroscopy

“…In the fitting process, the initial values used for the ground state and upper state (m 12 = 1) constants of 13 C 12 CH 4 were average values calculated from the respective constants of the m 12 bands of 12 C 2 H 4 [17] and of 13 C 2 H 4 [22]. This is acceptable because the rovibrational structure of all three molecules is expected to be very similar and free from local frequency perturbations [17,22].…”

“…The nonlinear least-squares program which was previously used for the m 12 bands of 12 C 2 H 4 [17] and of 13 C 2 H 4 [22] was also employed to fit the assigned transitions of m 12 of 13 C 12 CH 4 . That program for fitting asymmetric rotor spectra uses a Watson Hamiltonian [27] with an I r representation in an A-reduction.…”

“…Since the rovibrational constants for m 12 = 1 state of 13 C 12 CH 4 were not available, initial assignment of the transitions could be made with the knowledge of the rovibrational constants of m 12 bands of 12 C 2 H 4 [17] and of 13 C 2 H 4 [22]. These assignments were initially made for the transitions with low J values.…”

“…Furthermore, many higher resolution infrared measurements and analyses [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] of the fundamental, overtone, and combination bands of these molecules were conducted mainly to study their rovibrational structures and to determine their rotational and higher order constants with high accuracy. Most of the latest high-resolution FTIR studies are centred on 12 C 2 H 4 [7,17], 12 C 2 D 4 [8,9,[14][15][16], trans-12 C 2 H 2 D 2 [10,19], cis-12 C 2 H 2 D 2 [11,18], 1,1-ethylene-d 2 [20,21], and 13 C 2 H 4 [22]. However, infrared spectroscopic studies on 13 C 12 CH 4 remain very limited.…”

“…Likewise, we had studied the m 12 bands of 12 C 2 D 4 [14], of cis-12 C 2 H 2 D 2 [18], of trans-12 C 2 H 2 D 2 [19], of 13 C 2 H 4 [22] and of 12 C 2 H 3 D [25] at high-resolution to improve on or to derive new ground and m 12 = 1 rovibrational constants. The present work is aimed at the analysis of the m 12 band of 13 C 12 CH 4 which was measured with a resolution of 0.0063 cm À1 .…”