The near infrared electronic spectrum of tungsten methylidyne, WCH

Abstract

High sensitivity and precision spectroscopy in the far infrared AIP Conf.The laser excitation spectrum of tungsten methylidyne, WCH, has been recorded in the 12 000-15 400 cm Ϫ1 region. A total of 14 vibronic bands of WCH and 16 bands of WCD have been observed in this region. Rotational analysis shows that the ground state is X3/2( 2 ⌬), with the substitution structure r 0 ͑WwC͒ϭ1.7366 5 Å and r 0 ͑C-H͒ϭ1.076 5 Å. The excited vibronic levels have been assigned, on the basis of their WCH/WCD isotope shifts and their wavelength resolved fluorescence patterns, to three electronic states, Ã3/2( 2 ⌬), B1/2( 2 ⌸), and C 5/2( 2 ⌽), at 12 090, 13 392, and 14 110 cm Ϫ1 , respectively. The wavelength resolved fluorescence spectra have also established the low-lying vibrational levels of the ground state. The ground state bending fundamental lies at 660 cm Ϫ1 , while the W-C stretching frequency is 1006 cm Ϫ1 ; the corresponding frequencies in WCD are 501 cm Ϫ1 and 953 cm Ϫ1 , respectively. No evidence for the C-H stretching frequency has been found. Emission has also been observed to a low-lying electronic state, 813 cm Ϫ1 above the X3/2 state. The pattern of rotationally resolved emission to this state clearly indicates that it is a 4 ⌺ 1/2 state. Its bending frequency is 612 cm Ϫ1 , and its W-C stretching frequency is 971 cm Ϫ1 , indicating a slightly longer bond length than in the X3/2 state. High resolution cw laser spectra of the ͑0,0͒ bands of the two lowest excited electronic states ͓Ã3/2( 2 ⌬) and B1/2( 2 ⌸)͔ reveal a small splitting of the four principal tungsten isotopes ͑ 182 W, 183 W, 184 W, and 186 W͒ which serves to confirm the presence of tungsten in the carrier. Hyperfine splitting associated with the 183 W nucleus (Iϭ1/2) has been observed for the ͑0,0͒ band of the Ã3/2ϪX3/2 system, allowing the electron configuration of the ground state to be elucidated.

2Π–X2Σ+Electronic Bands of Titanium Methylidyne, TiCH, near 725 nm Wavelength

“…This is the more nearly equal, the more the electron probability density builds up between the two atoms. In turn this similar to the WCH spectrum (18), where the bond length changes are also small. However, in WCH the wave-depends on the magnitude of the ''bond integral'' between the atoms and the zero order separation of the length-resolved fluorescence patterns are completely characteristic for the upper state vibrational quantum atomic orbital energies.…”

Rotational analysis of the $3_0^1 $31 band of the $\tilde A{}^6\Sigma ^ + \leftarrow \tilde X{}^6\Sigma ^ + $Ã6Σ+←X̃6Σ+ system of CrCCH

“…This parameter has been measured to be 47 cm −1 in the B 6 state of CrF, 38 and a value of 50.6 cm −1 has been obtained in ab initio studies of CrCl. 47 In both CrF and CrCl, the B 6 state corresponds to a Cr + ion in its excited 3d 4 4s 1 , 6 D term interacting with a closed shell halide ion, with the Cr + electrons organized in a dδ 2 dπ 1 dσ 1 sσ 1 , 6 configuration. 44,48 In such a configuration, the spin-orbit constant, A, may be calculated using semi-empirical methods to be 1/5ζ 3d (Cr), which is expected to fall in the range 45-49 cm −1 .…”

“…A summary of previous spectroscopic work on diatomic transition metal carbides is provided in our recent study of diatomic VC. 2 More limited spectroscopic work is available on the transition metal methylidynes, MCH, where it appears that only TiCH, 3 VCH, 4 NbCH, 5 TaCH, 3 and WCH 6 have been investigated. Little gas phase spectroscopic work on the MCH 2 or MCH 3 neutral molecules has been reported, although the pure rotational spectrum of CuCH 3 has been measured 7 and vibronically resolved spectra of CrCH 3 and NiCH 3 have been reported.…”

Vibronic spectroscopy of unsaturated transition metal complexes: CrC2H, CrCH3, and NiCH3

“…[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] In addition to these pure metallic clusters and diatomic molecules, a handful of more complicated polyatomic organometallic radicals involving open d-subshell transition metals have been investigated using gas phase spectroscopic methods. These include the transition metal methylidynes TiCH, 23 VCH, 24 NbCH, 25 TaCH, 26 and WCH, 27 the dicarbide YC 2 , 28,29 the acetylide YbCCH, 30 and the cyanides CuCN 31 and NiCN. 32 Spectroscopic studies of filled ͑or empty͒ d-subshell organometallic radicals such as MgCH 3 , 33 CaCH 3 , 34 -36 SrCH 3 , 34,37 BaCH 3 , 38 ZnCH 3 , 39,40 CdCH 3 , 39,41,42 MgCCH, 43,44 CaCCH, [45][46][47] SrCCH, 45,48 NaCH, 49 KCH, 49 and CaC 5 H 5 50 have been very successful and abundant, but these molecules generally lack the connection to catalytic chemistry that is a primary motivatio...…”