Walter J. Balfour

Electronic spectroscopy of jet‐cooled iron monocarbide. The 3Δi←3Δi transition near 493 nm

We report the first gas phase spectroscopic study of iron monocarbide. FeC molecules were generated in a laser vaporization molecular beam source and detected by laser induced fluorescence. Twenty‐six vibronic bands have been recorded in the 430–500 nm region. Rotational analyses have been carried out for 22 of the bands. There are three lower states involved, two with Ω″=2 and one with Ω″=3. Based on our experimental observations and the ab initio calculations on RuC [Shim et al. J. Phys. Chem. 91, 3171 (1987)] the observed bands are interpreted as 3Δi←3Δi and 1Δ←1Δ transitions. The ground state electronic configuration is assigned to 1δ39σ1. Evidence for three excited electronic states (one 3Δi state, one 1Δ state and another state with Ω′=3) and for perturbations in several of their vibrational levels is presented.

The vibrational spectrum of anisole

Abstract The infrared and Raman spectra of C6H5OCD3, C6D5OCH3 and C6D5OCD3 have been recorded in the liquid state. Vibrational assignments have been made and values for most of the fundamental vibrations have been obtained and correlated with those of C6H5OCH3. Studies of the ultraviolet absorption spectrum have provided gas-phase data on a number of totally symmetric modes.

The near-infrared spectrum of the FeH molecule

The rotational analysis has been carried out on seven bands of the 4 Delta-4 Delta system of the FeH molecule. In order of wavelength of the heads they are (2-0) at 7786 A, (1-0) at 8692 A, (2-1) at 9020 A, (0-0) at 9896 A, (1-1) at 10253 A, (0-1) at 11939 A, and (1-2) at 12389 A. Molecular constants, term values, spin splittings, and Lambda-type doublings have been derived. Calculated wavelengths and wavenumbers are presented for the (2-2) and (0-2) bands with heads at 10639 and 14927 A, respectively. Finding lists of lines in the observed bands are provided to aid in astronomical applications. 19 references.

Rotational, fine, and hyperfine analyses of the (0,0) band of the D 3Π–X 3Δ system of vanadium mononitride

The VN molecule has been produced in a molecular beam apparatus using a laser vaporization source and its D 3Π–X 3Δ(0,0) band has been studied by laser‐induced fluorescence at low (∼0.1 cm−1) and sub‐Doppler resolution (∼0.004 cm−1). Lifetimes of single rotational levels of the D 3Π0 component have been measured and interpreted. Rotational, fine, and hyperfine structures in six of the nine subbands possible for a 3Π ← 3Δ transition have been recorded. Both states exhibit a rapid transition from case (a) → case (b) coupling cases, manifested by reversals in the Lande patterns of the hyperfine structure. The data have been reduced to a set of 35 molecular constants using a modified case (aβ) effective Hamiltonian in which two additional magnetic hyperfine parameters are required for each state. The distortions in the hyperfine structure are due almost entirely to second‐order spin–orbit interaction between states arising from the same configuration. Analysis of the derived parameters indicates that the X 3Δ...

Laser‐induced fluorescence spectroscopy of the à 1Πu–X̃ 1Σ+g transition in jet‐cooled C3

C3 radicals have been produced in a plasma of rhenium with methane doped in helium and cooled in a supersonic free jet expansion. More than 50 vibronic bands in the laser induced fluorescence spectrum of the A 1Πu–X 1Σ+g electronic transition have been recorded in the region 370–415 nm at 0.4 cm−1 resolution. The observations include bands identified by Gausset et al. (1965) and many bands not previously characterized. Rotational analyses have been made for a majority of the bands and the number of located Renner–Teller levels of the A state has been considerably extended. The (002) level is tentatively identified. A comparison of the experimentally determined energy level pattern in the A state with theoretical predictions has suggested a number of revisions to previous assignments and evidence is presented to contradict suggestions from earlier work that the (020) level of the A state is perturbed.

Jet-cooled optical spectroscopy of yttrium monocarbide: Evidence for a 4Πi ground state

Abstract The first observation of yttrium monocarbide, YC, is reported. A number of vibronic bands have been observed in the 635–650 nm region. Four of these bands have been investigated at a resolution of 120 MHz, and rotational constants have been derived. The bands originate from a common lower Ω = 5 2 state which, on the basis of recent ab initio calculations [Shim, Pelino and Gingerich, J. Cheni. Phys. 97 (1992) 9240], is the lowest lying spin-orbit component of the ground 4Πi state. This state arises from a ⋯10σ211σ112σ15π3 electron configuration. The nature of the excited states is also discussed.

Spectroscopy of the indium argon van der Waals complex: A high resolution study of the B 2Σ1/2←X2 2Π3/2 system

The InAr van der Waals complex has been characterized by high resolution laser induced fluorescence excitation spectroscopy. Six vibronic bands of the B 2Σ1/2←X2 2Π3/2 transition have been observed and five of these (v’,0), where v’=1–5, have been rotationally analyzed. Rydberg–Klein–Rees potential curves were constructed for the B 2Σ1/2 state using the rotational and vibrational constants determined from these spectra. Equilibrium bond lengths were determined for the B and X2 states and a dissociation energy was determined for the B state. The stronger bonding present in the B state is rationalized in terms of penetration of the argon atom into the diffuse 6s orbital of indium. Evidence is presented that the B state potential energy curve has a barrier at long range, due to Pauli repulsion, of ∼60 cm−1. An analysis of the hyperfine structure involving the 115In nucleus was made. It is concluded that the X2 state conforms to Hund’s coupling case aβ, whereas the B state conforms to case bβs. The extent of ...

Low-lying electronic states of magnesium hydride

Abstract A new 2 Σ + -X 2 Σ + transition in MgH has been found in emission. The upper state of this system lies lower in energy than any of the previously identified excited 2 Σ + states of MgH. The 2 Σ + state is relatively weakly bound at large internuclear distance. This discovery allows a reinterpretation to be made of the MgH electronic state manifold and its correlation with the states of the separated atoms and provides an explanation for some puzzling and long-standing observations in the MgH electronic spectrum.

First observation and electronic spectroscopy of chromium mononitride: The A 4Πr←X 4Σ− transition near 745 nm

We report the first gas phase spectroscopic study of chromium mononitride. CrN molecules were generated in our laser vaporization molecular beam source and studied using laser induced fluorescence techniques. Twelve vibronic subbands of Cr14N have been rotationally analyzed in the 745–647 nm region. These bands are assigned to the A 4Πr←X 4Σ− transition. The assigned ground state electron configuration 1δ29σ1 and symmetry are identical to those of the isovalent VO, MoN, and WN molecules. The energy observed for the excited 4Πr state matches closely the first 4Π state energy derived from a recent ab initio calculation [J. F. Harrison, J. Phys. Chem. 100, 3513 (1996)]. In addition to the A-X transition, 11 other bands of Cr14N have been identified and vibrationally assigned to transitions involving two other excited states, presumably the B4Σ−, and a 2Π state. Comparisons with the isovalent VO, MoN, and WN systems have provided more insights into the bonding and electronic structure of the CrN molecule.

The rotational analysis of the gamma system (A 3Φ - X′ 3Δ) of the spectrum of zirconium oxide

Abstract Rotational analyses of the (0,0), (1,1) and (2,2) bands, and a partial analysis of the (3,3) band, of the γ-system ( A 3 Φ - X ′ 3 Δ) of the molecules 90 Zr 16 O, 94 Zr 16 O, 96 Zr 16 O have been performed. The measured wave numbers and their assignments are presented up to high quantum numbers. The rotational constants are calculated and an estimate is made of the spin-coupling coefficients. Both states belong closely to Hunds coupling case a .