B Lindgren

Spectroscopy of TiH: Rotational analysis of the 4Γ→X 4Φ (0,0) band at 530 nm

Emission bands of the TiH radical in the region 18 000–20 000 cm−1 have been recorded both with grating spectrograph and Fourier transform techniques. The rotational structure of the 530 nm band, which is the strongest one of the three observed bands, has been analyzed and molecular parameters have been derived for the electronic states involved. The electronic assignment of this band is confirmed as 4Γ→X 4Φ, with a heavily perturbed upper state. The principal parameters (cm−1) of the analyzed states are X 4Φ (v=0): A=33.083(29), B=5.362 06(19), and γ=0.1823(27). 4Γ (v=0): T=18 878.10(47), A=41.54(10), B=5.7408(22), γ=−4.33(12), and λ=0.77(14). The derived first order spin–orbit parameter values of X 4Φ and 4Γ are shown to be consistent with the electronic configurations δπσ and δππ′, respectively. The local perturbations in the 4Γ state are discussed and arguments are given to suggest that the dominating perturber is of 4Φ symmetry.

On the Λ-type Doubling in the Ground State of SiH

The (0, 0) band of the 2?-2? transition of SiH has been remeasured from high-dispersion plates and more precise values of the ?-doubling parameters for the 2? state have been determined. From these optical measurements the transition between the two components of the lowest rotational level can be predicted to lie at 2968 ? 6 MHz.

R2PI detection of the quantum yields of I(2P1/2) and I(2P3/2) in the photodissociation of C2F5I, n-C3F7I, i-C3F7I and CH3I

Abstract Resonant two-photon ionization R2PI has been applied to the measurements of the quantum yields ϕ of iodine atoms in the fine structure states 2 P 1/2 and 2 P 3/2 arising in the UV-photodissociation process ( λ =266 and 355 nm) of the perfluoroalkyliodides C 2 F 5 I, n -C 3 F 7 I and i -C 3 F 7 I as well as of methyl iodide CH 3 I ( λ =266 nm). The measured values of the quantum yields of the excited state ( 2 P 1/2 ) of the I atoms are found to be ϕ 266 ∗ =0.921±0.010 and ϕ 355 ∗ =0.178±0.025 for C 2 F 5 I, ϕ 266 ∗ =0.919±0.011 and ϕ 355 ∗ =0.296±0.029 for n -C 3 F 7 I, ϕ 266 ∗ =0.900±0.015 and ϕ 355 ∗ =0.396±0.034 for i -C 3 F 7 I, and ϕ 266 ∗ =0.71±0.03 for CH 3 I. The results obtained show that the quantum yield ϕ 266 ∗ of the excited state atoms I( 2 P 1/2 ) in the photodissociation process of the perfluoroalkyliodides differs noticeably from unity which has previously been assumed or measured for these molecules.

Ultraviolet Absorption Spectrum of the CaH Molecule II. The structure of the d-complex around 2 850 Å

The absorption bands of CaH at 2 883 and 2 852 A have together with a new band at 2 821 A been interpreted as a transition from a d-complex to the ground state X2Σ+. A Hamiltonian matrix has been constructed for the three upper states G2Σ+, J2Π and M2Δ and the constants for the deperturbed states have been evaluated. The constants reproduce the observed term values within 0.2 cm-1. The ionisation potential of CaH is estimated to 47 250 ± 750 cm-1.

Ultraviolet Absorption Spectrum of the CaH Molecule. I. Rotational Analysis of the 3 060 A Band System

Four new violet degraded bands of CaH have been observed in absorption in the region 2 900 to 3 200 A by heating calcium and hydrogen to 1 200-1 400°C. Rotational analysis indicates that the bands belong to two close-lying systems K2Σ+ - X2Σ+ and L2Π - X2Σ+ which are separated by similar 50 cm-1 for the 0-0 bands. The rotational levels for the excited states approximate to Hunds case (d) coupling with L = 1. A Hamiltonian matrix has been constructed for the two states and constants for the unperturbed states evaluated. These constants reproduce the experimental term values to within 0.2 cm-1, except for levels involved in local perturbations.

Resonant two-photon ionization spectroscopy studies of jet-cooled

Resonant two-photon ionization spectroscopy in a jet-cooled molecular beam has been employed for the study of the zirconium dimer produced by laser ablation. More than 110 resonances have been observed in the wavelength region 610-1070 nm. Most of these resonances are transitions from of the ground state, which is shown to be a state, to different vibrational levels of the excited states. Three bands have been rotationally analysed. The ground state B-value is found to be . Radiative lifetimes have been measured for two excited states, both of them between 1 and .

Rotational Analysis of the Spectra of SbH and SbD

The A3Πi-X3Σ- transitions have been studied in SbH and SbD. The spectra were obtained after flash photolysis of stibine and deuterostibine. The ground state is separated into two sub-states and is described in terms of Hunds coupling case (c). The splitting between the X0+ and X 1 sub-states is 660 cm-1. The upper state 3Πi is predissociated and only the 3Π0+ substate show rotational structure (but a few levels in 3Π2 of SbD). A second upper state B0+ and a third upper state C0+, only observed in SbD, causes perturbations to the 3Π0+ sub-state. Molecular constants have been derived where possible.

The Vacuum Ultraviolet Spectrum of Selenium Hydride I. Determination of the Ground State Spin-Orbit Coupling Constant

In the wavelength region 1700-1900 A an electronic transition in the SeH (SeD) molecule is observed. Even though the bands are so diffuse that the rotational structure is almost unresolved, the transition can be identified as the B2Σ-X2Πi system and a good determination of the spin-orbit coupling constant A = -1764.4 ± 0.2 cm-1 can be made.

Resonant tow-photon ionization detection of atomic iodine resulting from photodissociation of allyl iodide under vibrational (C-H overtone) excitation

Abstract The resonant two-photon ionization (R2PI or (1 + 1) REMPI) method was used to achieve highly sensitive detection of atomic iodine. The atoms were excited and ionized by tuned VUV and visible radiation, subsequently. The formation of iodine atoms in the fine structure states 2 P 3 3 2 and 2 P 1 2 was observed after the photolysis of allyl iodide (C 3 H 5 I) by UV radiation (355 nm). The atomic iodine absorption at 151.469 and 159.358 nm corresponding to the transitions 2 P 3 2 -( 3 P 2 ) 5d[3] 5 2 and 2 P 1 2 - 3 P 2 5d[2] 3 2 , respectively, were obtained under both collisional and collisionless conditions. It was shown, that the distribution of I atoms on hyperfine structure levels, produced from the photodissociation of C 3 H 5 I did not differ from the equilibrium one. The time-profile of atomic iodine appearance was measured when C 3 H 5 I was excited at the CH vibrational overtone frequency (υ=5, λ=703.5 nm).

Ultraviolet Absorption Spectrum of the CaH Molecule. IV. On the C-X System

An investigation of the (1, 0) sequence of the C2Σ-X2Σ system of CaH reveals that higher vibrational levels of the C2Σ state are unlikely to be responsible for the perturbations in the K2Σ state as earlier presumed. An identification of the (13, 0) band of the D2Σ-X2Σ system at 3482 A is also reported.