Global fit analysis including the ν9+ν4−ν4 hot band of ethane: Evidence of an interaction with the ν12 fundamental

Vibration–rotation–torsion analysis of the high resolution infrared spectrum of C2H6 between 1330 and 1610cm−1: The ν6, ν8, ν4+ν12, 2ν4+ν9 interacting system and hot transitions from ν4 to ν4+ν8

“…This is in full agreement with the increase Table 1 Vibration-rotation-torsional parameters for the matrix elements within a given vibrational state in the m 8 , m 6 , m 4 + m 12 , 2m 4 + m 9 system of C 2 H 6 of the barrier height with the excitation of m 9 , predicted theoretically [33] and observed experimentally [9,10,35]. The magnitude of the torsional splitting 3X in this state, about 2.74 cm À1 , is consistently smaller than in the 2m 4 state (about 4 cm À1 ).…”

“…Nonetheless, a detailed high resolution rotational-torsional analysis of vibrational transitions of ethane could be performed only for the lowest infrared active fundamental m 9 , the asymmetric CH 3 rocking mode [5][6][7][8][9] centred around 821 cm À1 . Very recently Cooper and Moazzen-Ahmadi were able to complete a global fit analysis of the m 9 band, together with the (m 9 + m 4 ) À m 4 hot band, the CAC stretching fundamental m 3 near 994 cm À1 and the m 4 , 2m 4 À m 4 and 3m 4 torsional bands [10]. In all the other regions the complexity of the spectrum, with the occurrence of several resonances, has hindered so far a reliable detailed analysis.…”

The HITRAN2012 molecular spectroscopic database

“…It was generated by Vander Auwera et al [246] using a spectrum of the ν 9 band recorded at the Pacific Northwest National Laboratory [228], and results from a global analysis of data involving the four lowest vibrational states of ethane [247] and measurements of pressure-broadening parameters [248,249]. Note that the quantum number notation for representing rotation-torsion states has been converted to HITRAN formalism.…”

The band of ethane: A global frequency analysis of data from the four lowest vibrational states

“…We have therefore carried out systematic studies of the three lowest vibrational states of ethane. In previous contributions, we have reported global-fit studies including data from only torsional transitions in the ground vibrational state (gs) [10]; from the gs and the m 9 fundamental [11]; from the gs and the m 9 and m 3 (C-C stretch) fundamentals [12]; and from the gs, the m 9 and m 3 fundamentals and the m 9 þ m 4 À m 4 band [13]. Two global-fits were presented in Ref.…”