Velocity modulation diode laser spectroscopy of negative ions: The ν1, ν1+ν2−ν2, ν1+ν3−ν3 bands of thiocyanate (NCS−)

149 transitions in the ν1 band (CN stretch) and the corresponding bending and stretching hot bands of thiocyanate (NCS−) have been measured using velocity modulation spectroscopy with a tunable diode laser. The data were fit to an effective rotation–vibration Hamiltonian, yielding spectroscopic parameters for the (000), (100), (010), (110), (001), and (101) vibrational states. The band origin is ν1=2065.9312(13) cm−1 and the equilibrium rotational constant is calculated to be 0.197 438(61) cm−1. NCS− was prepared in a NH3/CS2 discharge, and unlike the recently studied case of NCO−, vibrational excitation in excess of the rotational temperature (650±200 K) was not observed.

[1]  M. Gruebele,et al.  Diode laser velocity modulation spectroscopy of carbanions: The CC stretching vibration of C2H− , 1987 .

[2]  M. Gruebele,et al.  Velocity modulation laser spectroscopy of negative ions. The .nu.3 band of azide anion , 1987 .

[3]  G. Frenking,et al.  Theoretical investigation of the structures and electron affinities of cyanato and thiocyanato isomers, 2-azallyl, and methanimine , 1987 .

[4]  M. Gruebele,et al.  Determination of the Born–Oppenheimer potential function of CCl+ by velocity modulation diode laser spectroscopy , 1986 .

[5]  M. Gruebele,et al.  Velocity modulation laser spectroscopy of vibrationally excited CF+: determination of the molecular potential function , 1986 .

[6]  J. Owrutsky,et al.  The vibration-rotation spectrum of the hydroxide anion (OH - ) , 1985 .

[7]  J. Johns,et al.  High-resolution spectroscopy of 16 bands of OCS in the region 1975–2140 cm−1 for diode laser calibration , 1985 .

[8]  V. Bierbaum,et al.  Gas-phase synthesis and reactions of nitrogen- and sulfur-containing anions , 1984 .

[9]  R. Saykally,et al.  Velocity Modulation Infrared Laser Spectroscopy of Molecular Ions , 1984 .

[10]  D.Foss Smith.  Infrared spectra of 15NCS− in the alkali halides , 1975 .

[11]  J. Dillard,et al.  Reactions of Negative Ions in the Gas Phase. II. NH2 , 1968 .

[12]  F. M. Page,et al.  Determination of electron affinities. Part 5.—Cyanide and thiocyanate radicals , 1963 .

[13]  W. Price,et al.  Infra-red studies on polyatomic ions isolated in alkali-halide lattices , 1960 .

[14]  L. H. Jones.  Infrared Spectrum and Structure of the Thiocyanate Ion , 1956 .

[15]  Dudley H. Williams,et al.  The Infrared Absorption of Cyanides and Thiocyanates , 1935 .