C. R. Brazier

Fourier transform spectroscopy of the A3Π-X3Σ− transition of NH

Abstract The A3Π-X3Σ− transition of NH has been observed using a high-resolution Fourier transform spectrometer. The first three vibrational levels in each state were observed and the vibrational, fine structure, and rotational constants obtained.

Spectroscopy of the CH free radical

Abstract New emission observations of the A 2 Δ- X 2 Π and B 2 Π − - X 2 Π electronic transitions of the CH free radical were recorded. The A 2 Δ- X 2 Π and B 2 Σ − - X 2 Π data were obtained with a Fourier transform spectrometer and additional measurements of the A 2 Δ- X 2 Π transition were made with a spectrograph. These line positions were combined with the previous infrared vibration-rotation measurements in a simultaneous fit to determine the molecular parameters for the X 2 Π, A 2 Δ, and B 2 Σ − states.

The infrared spectrum of XeH

The Fourier transform emission spectrum of XeH+ was observed in the infrared region of the spectrum. The 1–0 and 2–1 vibration–rotation bands for 132XeH+, 131XeH+, and 129XeH+ were recorded from a nickel hollow cathode discharge in xenon and hydrogen. Molecular constants, including Re=1.602 813(6) A, Be=6.560 686(50), αe=0.186 739(14), ωe=2269.9674(11), and ωexe=41.328 30(34) cm−1 for 132XeH+, were extracted from the line positions. Our work represents the first high‐resolution detection of XeH+.

Fourier transform spectroscopy of the ν3 band of the N3 radical

We have analyzed the ν3 antisymmetric stretching fundamental of the N3 radical. Azide radicals N3 were generated in a multipass cell by the reaction of Cl atoms and HN3 and detected in absorption using a Fourier transform spectrometer. Improved constants for the 000 vibrational level of X 2Πg are reported along with observations of the 001 level. The frequency of the ν3 fundamental at 1645 cm−1 was found to be somewhat lower than expected.

The à 2E–X̃ 2A1 transition of monomethyl calcium: A rotational analysis

The 000 band of the A 2E–X 2A1 transition of CaCH3 has been rotationally analyzed at Doppler‐limited resolution by laser excitation spectroscopy. Observation of an internal perturbation in the excited state permitted simultaneous determination of both A’ and A‘. The ground‐state molecular structure was found to be RCa–C=2.349(13) A and θH–C–H=105.6(28)° with RC–H fixed at 1.100(20) A.

Rotational analysis of the B̃ 2Σ+–X̃ 2Σ+ transition of BaOH and BaOD

The B 2Σ+–X 2Σ+ transitions of BaOH and BaOD were studied by the technique of dye laser spectroscopy. The 000–000 and 001–000 bands of BaOH and 000–000 band of BaOD were rotationally analyzed. The B 2Σ+ state is perturbed by the A 2Π state and each parity (e/f) component of the B state was fit separately. BaOH is a linear molecule with r0(Ba–O)=2.201 A and r0(O–H)=0.923 A. The X 2Σ+ vibrational frequencies for BaOH (BaOD) are 492.4 (482.4) cm−1 for Ba–O stretch and 341.6 (257.6) cm−1 for the bend.

The A 3Σ−–X 3Π transition of the SiC radical

The 0–0 band of the A 3 Σ−–X 3 Π system of SiC, analogous to the Ballik–Ramsay system of C2, has been observed in emission near 4500 cm−1. The internuclear separations (r0 ) were found to be 1.813 56 and 1.721 87 A for the A 3 Σ− and X 3 Π states, respectively.

Observation of gas phase organometallic free radicals: Monomethyl derivatives of calcium and strontium

We have observed the organometallic free radicals CaCH3 and SrCH3 by the gas phase reaction of Ca or Sr metal vapor with Hg(CH3)2 and several other CH3 containing oxidants. The positions of the A 2E–X 2A1 and B 2A1–X 2A1 transitions were determined, as well as several vibrational frequencies. The observation of predissociation in the A 2E state gives an upper limit of 46 kcal/mol (43 kcal/mol) to the bond dissociation energy for CaCH3 (SrCH3).

Laser spectroscopy of calcium and strontium monoacetylides

Abstract The gas-phase free radicals CaCCH and SrCCH were synthesized by the reaction of Ca or Sr vapor with HCCH. The electronic and vibrational structure of these molecules were investigated by laser excitation spectroscopy and laser-induced fluorescence. These ionic metal acetylides proved to be linear in geometry.

Rotational analysis of the Ã2Π-X̃2Σ+ transition of calcium monoacetylide, CaCCH

Abstract The 0-0 band of the A 2 Π - X 2 Σ + transition of the CaCCH molecule was rotationally analyzed by dye laser excitation spectroscopy with narrow band fluorescence detection. The rotational constants extracted from the line positions enabled us to estimate the Ca-C bondlength to be 2.25 A in the ground electronic state. This work represents the first high-resolution analysis of a metal acetylide molecule.