Junfeng Zhen

Photolysis of n-butyl nitrite and isoamyl nitrite at 355 nm: A time-resolved Fourier transform infrared emission spectroscopy and ab initio study

We report on the photodissociation dynamics study of n-butyl nitrite and isoamyl nitrite by means of time-resolved Fourier transform infrared (TR-FTIR) emission spectroscopy. The obtained TR-FTIR emission spectra of the nascent NO fragments produced in the 355 nm laser photolysis of the two alkyl nitrite species showed an almost identical rotational temperature and vibrational distributions of NO. In addition, a close resemblance between the two species was also found in the measured temporal profiles of the IR emission of NO and the recorded UV absorption spectra. The experimental results are consistent with our ab initio calculations using the time-dependent density functional theory at the B3LYP/6-311G(d,p) level, which indicate that the substitution of one of the two gamma-H atoms in n-C(4)H(9)ONO with a methyl group to form (CH(3))(2)C(3)H(5)ONO has only a minor effect on the photodissociation dynamics of the two molecules.

Experimental Determination of the Vibrational Constants of FeS(X5Δ) by Dispersed Fluorescence Spectroscopy

Based on previous laser-induced fluorescence excitation spectroscopy work, the vibrational constants of neutral FeS in the X5Δ electronic state were obtained by directly mapping the ground-state vibrational levels up to v″=3 using conventional laser-induced dispersed fluorescence spectroscopy. The vibrational frequency of FeS(X5Δ) (518±5 cm−1) agrees well with that reported in a recent PES measurement (520±30 cm−1) [J. Phys. Chem. A 107, 2821 (2003)] which is the only one prior experimental vibrational frequency value for the 5Δ state of FeS. Careful comparisons of our experimental results and those documented in the literature (mainly from theoretical predictions) suggest that the ground state of FeS is 5Δ state.

Line-profile analysis of excitation spectroscopy in the even 4p5(2P1/2)nl′ [K′] J (l′ = 1,3) autoionizing resonances of Kr

The even-parity autoionizing resonance series 4p5np′ [3/2]1,2, [1/2]1, and 4p5nf′ [5/2]3 of krytpon have been investigated by laser excitation from the two metastable states 4p55s [3/2]2 and 4p55s′ [1/2]0 in the photon energy region of 29000–40000 cm−1 at experimental bandwidth of ∼0.1 cm−1. The excitation spectra of the even-parity autoionizing resonance series, most of which are experimentally studied for the first time in this work, show typical asymmetric line shapes. Complementary information on level energies, quantum defects, line profile indices and resonance widths, resonance lifetimes and reduced widths of the autoionizing resonances are derived by Fano-type line-shape analyses of the experimental results. Results from this work indicate that the line profile index (q) and the resonance width (Γ) are approximately proportional to the effective principal quantum number (n*); the line separation of the 4p5np′ autoionizing resonances is also in good agreement with theoretical model.

Resonance‐Enhanced Photon Excitation Spectroscopy of the Even‐Parity 3p5(2P1/2)nl′ [K′]J (l′=1, 3) Autoionizing Rydberg States of Ar

Metastable 40Ar* atoms are produced in the two metastable states 3p54s [3/2]2 and 3p54s′ [1/2]0 in a pulsed DC discharge in a beam, and are subsequently excited to the even‐parity autoionizing resonance series 3p5np′ [3/2]1,2, 3p5np′ [1/2]1, and 3p5nf′ [5/2]3 using single photon excitation with a pulsed dye laser. The excitation spectra of the even‐parity autoionizing resonance series from the metastable 40Ar* are obtained by recording the autoionized Ar+ ions with time‐of‐flight ion detection in the photon energy range of 32500–35600 cm−1 with an experimental bandwidth of <0.1 cm−1. A wealth of autoionizing resonances are newly observed, from which more precise and systematic spectroscopic data of the level energies and quantum defects are derived.

Laser-induced Fluorescence and Dispersed Fluorescence Spectroscopy of NiB: Identification of a New 2Π State in 19000–22100 cm−1

The laser-induced fluorescence excitation spectra of jet-cooled NiB radicals have been recorded in the energy range of 19000–22100 cm−1. Eleven bands have been assigned to the [20.77]2Π-X2Σ+ transition system for the first time. The dispersed fluorescence spectra related to most of these bands have been investigated. Vibrationally excited levels of the ground electronic state, with v″ up to 6, have been observed. In addition, the lifetimes for almost all the observed bands have also been measured.

Laser-induced Fluorescence Spectrum of CoS Between 15200 and 19000 cm?1

Laser-induced fluorescence excitation spectra of jet-cooled CoS molecules have been recorded in the energy range of 15200–19000 cm−1. Five transition progressions have been reported for the first time, the assignments of these progressions have been derived from a rotational analysis of vibronic bands and they are determined to be [15.58]4Δ7/2-X4Δ7/2, [16.02]4Δ7/2-X4Δ7/2, [16.50]4Δ7/2-X4Δ7/2, [17.80]4Π5/2-X4Δ7/2, and [18.00]4Δ7/2-X4Δ7/2 transitions. In addition, under the supersonic jet condition the fluorescent lifetimes of these vibronic states were measured by exponentially fitting the fluorescence decay. Based on the observed spectra and the measured lifetimes of the vibronic states, the newly identified electronic states are discussed.

Laser-induced Fluorescence Excitation Spectrum of NiS in 1550017200 cm1

The laser-induced fluorescence excitation spectrum of jet-cooled NiS molecule has been recorded in the energy range of 1550017200 cm1. Fifteen bands have been assigned as three transition progressions: [15.65]31(v = 04)-X30(v = 0), [15.69]30(v = 04)-X30(v = 0), and [15.81]31(v = 04)-X30(v = 0). Spectroscopic constants for the three newly identified electronically excited states have been determined for the first time. In addition, the lifetimes for most observed vibronic bands have also been measured.

Resonance-Enhanced Photon Excitation Spectroscopy of the Even-Parity Autoionizing Rydberg States of Xe

Kr atoms were produced in their metastable states 4p55s [3/2]2 and 4p55s’ [1/2]0 in a pulsed DC discharge in a beam, and subsequently excited to the even-parity autoionizing Rydberg states 4p5np′ [3/2]1,2, [1/2]1 and 4p5nf′ [5/2]3 using single photon excitation. The excitation spectra of the even-parity autoionizing resonance series from the metastable Kr were obtained by recording the autoionized Kr+ ions with time-of-flight ion detection in the photon energy range of 29000–40000 cm−1. A wealth of autoionizing resonances were newly observed, from which more precise and more systematic spectroscopic data of the level energy and quantum defects were derived.

Line‐profile Analysis of Excitation Spectroscopy in Even 5p5(2P1/2)nl′ [K′]J (l′=1, 3) Autoionizing Resonances of Xe

The even-parity autoionizing resonance series 5p5np′ [3/2]1, [1/2]1, and 5p5nf′ [5/2]3 of xenon have been investigated, excited from the two metastable states 5p6s [3/2]2 and 5p56s′ [1/2]0 in the photon energy range of 28000−42000 cm−1 with experimental bandwidth of ∼0.1 cm−1. The excitation spectra of the even-parity autoionizing resonance series show typical asymmetric line shapes. New level energies, quantum defects, line profile indices and resonance widths, resonance lifetimes and reduced widths of the autoionizing resonances are derived by a Fano-type line-shape analysis. The line profile index and the resonance width are shown to be approximately proportional to the effective principal quantum number. The line separation of the 5p5np′ autoionizing resonances is discussed.