Rotational and rovibrational spectroscopy of CH3NC of the ground and ν4 = 1 vibrational states.
The parallel vibration-rotation band ν(4) of methyl isocyanide (CH(3)NC), with a band center at 944.9 cm(-1), was studied by FTIR spectroscopy between 890 and 980 cm(-1) in order to improve the ground-state rotational constants. Such improvement is essential for the scheduled studies of excited vibrational levels and their mutual anharmonic resonances occurring at higher values of the K rotational number. Ground-state combination differences generated from this band, spanning values of J/K from 0 to 85/13, were combined with rotational data from the literature and newly measured rotational transitions, extending the J/K range from 3/0 up to 31/14, and fitted simultaneously with a fully quantitative reproduction of the data. The infrared data of the ν(4) band were analyzed together with rotational data of the ν(4) = 1 level, spanning values of J/K from 4/0 to 14/12. The fit in the approximation of an isolated vibrational state, with the transitions perturbed by weak local resonances excluded, yields reproduction of the data within experimental uncertainties.
J. Heyrovský Institute of Physical Chemistry, vvi, Academy of Sciences of the Czech Republic, Prague, Czech Republic. pracna@jh-inst.cas.cz
Petr
P
Pracna
Jirí
J
Urban
Ondrej
O
Votava
Zuzana
Z
Meltzerová
Stepán
S
Urban
Veli-Matti
VM
Horneman
Brian J
BJ
Drouin