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Liu M, Jiang P, Cheng M, Gao H. Vacuum ultraviolet photoexcitation and photofragment spectroscopic studies of 14N 15N between 109000 and 117500 cm -1. J Chem Phys 2021; 155:234305. [PMID: 34937384 DOI: 10.1063/5.0072604] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this study, we employed a newly built time-slice velocity-map ion imaging setup, equipped with two tunable vacuum ultraviolet (VUV) laser sources, to obtain the first comprehensive high-resolution photoexcitation and photofragment excitation spectra of 14N15N in the VUV photon energy range 109 000-117 500 cm-1. The spectroscopic simulation program PGOPHER was used to analyze the rotationally resolved spectra. Band origins, rotational constants, and isotope shifts compared with those of 14N2 have been obtained for 31 electric-dipole-allowed vibrational states of 14N15N in the aforementioned energy range. These spectroscopic parameters are found to depend on the vibrational quantum number irregularly. Systematic perturbations of the rotational transition energies and predissociation rates within individual absorption bands have also been observed. These are proved to be caused by the strong homogeneous interactions between the valence b'1Σu + state and the Rydberg cn ' 1Σu + states, and between the valence b1Πu states and the Rydberg o3 1Πu states. Heterogeneous interactions between the Rydberg cn 1Πu states and cn ' 1Σu + states also play an important role.
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Affiliation(s)
- Min Liu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Pan Jiang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Min Cheng
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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2
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Heays AN, Lewis BR, de Oliveira N, Ubachs W. The spin-forbidden vacuum-ultraviolet absorption spectrum of 14N 15N. J Chem Phys 2019; 151:224305. [PMID: 31837671 DOI: 10.1063/1.5130206] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Photoabsorption spectra of 14N15N were recorded at high resolution with a vacuum-ultraviolet Fourier-transform spectrometer fed by synchrotron radiation in the range of 81-100 nm. The combination of high column density (3 × 1017 cm-2) and low temperature (98 K) allowed for the recording of weak spin-forbidden absorption bands' exciting levels of triplet character. The triplet states borrow intensity from 1Πu states of Rydberg and valence character while causing their predissociation. New predissociation linewidths and molecular constants are obtained for the states C3Πu(v = 7, 8, 14, 15, 16, 21), G3Πu(v = 0, 1, 4), and F3Πu(v = 0). The positions and widths of these levels are shown to be well-predicted by a coupled-Schrödinger equation model with empirical parameters based on experimental data on 14N2 and 15N2 triplet levels.
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Affiliation(s)
- A N Heays
- Department of Physics and Astronomy, and LaserLaB, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - B R Lewis
- Research School of Physics and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - N de Oliveira
- Synchrotron Soleil, Orme des Merisiers, St. Aubin, BP 48, 91192 Gif sur Yvette Cedex, France
| | - W Ubachs
- Department of Physics and Astronomy, and LaserLaB, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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3
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Symmetry of molecular Rydberg states revealed by XUV transient absorption spectroscopy. Nat Commun 2019; 10:5269. [PMID: 31754226 PMCID: PMC6872753 DOI: 10.1038/s41467-019-13251-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 10/29/2019] [Indexed: 11/08/2022] Open
Abstract
Transient absorption spectroscopy is utilized extensively for measurements of bound- and quasibound-state dynamics of atoms and molecules. The extension of this technique into the extreme ultraviolet (XUV) region with attosecond pulses has the potential to attain unprecedented time resolution. Here we apply this technique to aligned-in-space molecules. The XUV pulses are much shorter than the time during which the molecules remain aligned, typically \documentclass[12pt]{minimal}
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\begin{document}$$<$$\end{document}<100 fs. However, transient absorption is not an instantaneous probe, because long-lived coherences re-emit for picoseconds to nanoseconds. Due to dephasing of the rotational wavepacket, it is not clear if these coherences will be evident in the absorption spectrum, and whether the properties of the initial excitations will be preserved. We studied Rydberg states of N\documentclass[12pt]{minimal}
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\begin{document}$${}_{2}$$\end{document}2 and O\documentclass[12pt]{minimal}
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\begin{document}$${}_{2}$$\end{document}2 from 12 to 23 eV. We were able to determine the polarization direction of the electronic transitions, and hence identify the symmetry of the final states. Transient absorption spectroscopy is used to identify the structural characteristics of the atoms and molecules. Here the authors used extreme ultraviolet transient absorption spectroscopy to identify the Rydberg state symmetry of aligned molecules.
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Heays A, Lewis B, Gibson S, Stark G, de Oliveira N. Indirect predissociation of highly excited singlet states of N 2. EPJ WEB OF CONFERENCES 2015. [DOI: 10.1051/epjconf/20158403004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Muskatel BH, Remacle F, Levine RD. Ultrafast Predissociation Mechanism of the 1Πu States of 14N2 and Its Isotopomers upon Attosecond Excitation from the Ground State. J Phys Chem A 2012; 116:11311-8. [DOI: 10.1021/jp305354h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- B. H. Muskatel
- The Fritz Haber Research Center, Hebrew University, Jerusalem 91904, Israel
| | - F. Remacle
- The Fritz Haber Research Center, Hebrew University, Jerusalem 91904, Israel
- Director FNRS, Department
of Chemistry, B6c, University of Liege, B4000 Liege, Belgium
| | - R. D. Levine
- The Fritz Haber Research Center, Hebrew University, Jerusalem 91904, Israel
- Department of Chemistry
and Biochemistry, Crump Institute for Molecular Imaging,
and Department of Molecular and Medical Pharmacology, University of California, Los Angeles,
California 90095, United States
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6
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Heays AN, Dickenson GD, Salumbides EJ, de Oliveira N, Joyeux D, Nahon L, Lewis BR, Ubachs W. High-resolution Fourier-transform extreme ultraviolet photoabsorption spectroscopy of 14N15N. J Chem Phys 2012; 135:244301. [PMID: 22225150 DOI: 10.1063/1.3672165] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The first comprehensive high-resolution photoabsorption spectrum of (14)N(15)N has been recorded using the Fourier-transform spectrometer attached to the Desirs beamline at the Soleil synchrotron. Observations are made in the extreme ultraviolet and span 100 000-109 000 cm(-1) (100-91.7 nm). The observed absorption lines have been assigned to 25 bands and reduced to a set of transition energies, f values, and linewidths. This analysis has verified the predictions of a theoretical model of N(2) that simulates its photoabsorption and photodissociation cross section by solution of an isotopomer independent formulation of the coupled-channel Schrödinger equation. The mass dependence of predissociation linewidths and oscillator strengths is clearly evident and many local perturbations of transition energies, strengths, and widths within individual rotational series have been observed.
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Affiliation(s)
- A N Heays
- Institute for Lasers, Life and Biophotonics Amsterdam, VU University, Amsterdam, The Netherlands.
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On the strong and selective isotope effect in the UV excitation of N2 with implications toward the nebula and Martian atmosphere. Proc Natl Acad Sci U S A 2011; 108:6020-5. [PMID: 21441106 DOI: 10.1073/pnas.1102767108] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Isotopic effects associated with molecular absorption are discussed with reference to natural phenomena including early solar system processes, Titan and terrestrial atmospheric chemistry, and Martian atmospheric evolution. Quantification of the physicochemical aspects of the excitation and dissociation processes may lead to enhanced understanding of these environments. Here we examine a physical basis for an additional isotope effect during photolysis of molecular nitrogen due to the coupling of valence and Rydberg excited states. The origin of this isotope effect is shown to be the coupling of diabatic electronic states of different bonding nature that occurs after the excitation of these states. This coupling is characteristic of energy regimes where two or more excited states are nearly crossing or osculating. A signature of the resultant isotope effect is a window of rapid variation in the otherwise smooth distribution of oscillator strengths vs. frequency. The reference for the discussion is the numerical solution of the time dependent Schrödinger equation for both the electronic and nuclear modes with the light field included as part of the Hamiltonian. Pumping is to all extreme UV dipole-allowed, valence and Rydberg, excited states of N(2). The computed absorption spectra are convoluted with the solar spectrum to demonstrate the importance of including this isotope effect in planetary, interstellar molecular cloud, and nebular photochemical models. It is suggested that accidental resonance with strong discrete lines in the solar spectrum such as the CIII line at 97.703 nm can also have a marked effect.
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Moise A, Prince KC, Richter R. Time-resolved study of excited states of N2 near its first ionization threshold. J Chem Phys 2011; 134:114312. [PMID: 21428624 DOI: 10.1063/1.3560909] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Two-photon, two-color double-resonance ionization spectroscopy combining synchrotron vacuum ultraviolet radiation with a tunable near-infrared (NIR) laser has been used to investigate gerade symmetry states of the nitrogen molecule. The rotationally resolved spectrum of an autoionizing (1)Σ(g)(-) state has been excited via the intermediate c(4) (v = 0) (1)Π(u) Rydberg state. We present the analysis of the band located at T(v) = 10,800.7 ± 2 cm(-1) with respect to the intermediate state, 126,366 ± 11 cm(-1) with respect to the ground state, approximately 700 cm(-1) above the first ionization threshold. From the analysis a rotational constant of B(v) = 1.700 ± 0.005 cm(-1) has been determined for this band. Making use of the pulsed structure of the two radiation beams, lifetimes of several rotational levels of the intermediate state have been measured. We also report rotationally-averaged fluorescence lifetimes (300 K) of several excited electronic states accessible from the ground state by absorption of one photon in the range of 13.85-14.9 eV. The averaged lifetimes of the c(4) (0) and c(5) (0) states are 5.6 and 4.4 ns, respectively, while the b(') (12), c(')(4) (4, 5, 6), and c(')(5) (0) states all have lifetimes in the range of hundreds of picoseconds.
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Affiliation(s)
- Angelica Moise
- Sincrotrone Trieste, Area Science Park, I-34149 Basovizza, Trieste, Italy.
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Vieitez MO, Ivanov TI, Sprengers JP, Lange CAD, Ubachs W, Lewis BR, Stark G. Quantum-interference effects in the o1Πu(v=1)∼b1Πu(v=9) Rydberg–valence complex of molecular nitrogen. Mol Phys 2010. [DOI: 10.1080/00268970701291750] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Huber KP, Chan MC, Stark G, Ito K, Matsui T. N(2) band oscillator strengths at near-threshold energies. J Chem Phys 2009; 131:084301. [PMID: 19725610 DOI: 10.1063/1.3211309] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Band oscillator strengths for 58 bands in the near-threshold region of N(2), i.e., from 116 200 to 125 400 cm(-1), are derived from measured band-integrated optical depths. The complexity of the absorption spectrum demands that the measurements be carried out on rotationally cold supersonic jet expansions. The column density N in the absorbing path of the jet cannot be measured directly. Instead, the room temperature f values of selected calibration bands are used to convert the band-integrated optical depths of the jet-cooled calibration bands to preliminary column densities [N], which, plotted as a function of jet reservoir pressure p, scatter around a straight line passing through the origin of the graph. From the slope of the line, first estimates of the effective column density N can be derived for any value of p. Second estimates are obtained by repeating the same procedure using ab initio calculated f values based on the work of Spelsberg and Meyer [J. Chem. Phys. 115, 6438 (2001)]. Depending on the jet configuration, the two estimates differ by 3%-15%; their average is accepted as the best approximation to N. The derived band oscillator strengths are compatible with ab initio results of Spelsberg and Meyer and reproduce the observations reasonably well, even where two or more transitions combine in the formation of complex band structures. They also clarify the analysis of the absorption spectrum in the region of the 7p(0) complex [Jungen, Huber, Jungen, and Stark, J. Chem. Phys. 118, 4517 (2003)] and lead to a plausible interpretation of the spectrum in the 124 680-124 880 cm(-1) range. As a result, the lowest three vibronic levels of both the 3(')d(')sigma and the 4(')s(')sigma core excited states have now been identified.
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Affiliation(s)
- Klaus P Huber
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, K1A 0R6, Canada.
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11
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Liu X, Heays AN, Shemansky DE, Lewis BR, Feldman PD. Analysis of terrestrial thermospheric N2c′41Σu+(0) ∼b′1Σu+(1) −X1Σg+dayglow emission observed by the Far Ultraviolet Spectroscopic Explorer. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jd010403] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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12
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Lewis BR, Baldwin KGH, Sprengers JP, Ubachs W, Stark G, Yoshino K. Optical observation of the C, 3ssigma(g)F3, and 3ppi(u)G3 3Pi(u) states of N2. J Chem Phys 2008; 129:164305. [PMID: 19045264 DOI: 10.1063/1.2990655] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
High-resolution laser-based one extreme-ultraviolet (EUV)+one UV two-photon ionization spectroscopy and EUV photoabsorption spectroscopy have been employed to study spin-forbidden (3)Pi(u)-X (1)Sigma(g) (+)(v,0) transitions in (14)N(2) and (15)N(2). Levels of the C (3)Pi(u) valence and 3ssigma(g)F(3) and 3ppi(u)G(3) (3)Pi(u) Rydberg states are characterized, either through their direct optical observation, or, indirectly, through their perturbative effects on the (1)Pi(u) and (1)Sigma(u) (+) states, which are accessible in dipole-allowed transitions. Optical observation of the G(3)-X(0,0) and (1,0) transitions is reported for the first time, together with evidence for six new vibrational levels of the C state. Following the recent observation of the F(3)-X(0,0) transition at rotational resolution [J. P. Sprengers et al., J. Chem. Phys. 123, 144315 (2005)], the F(3)(v=1) level is found to be responsible for a local perturbation in the rotational predissociation pattern of the b(') (1)Sigma(u) (+)(v=4) state. Despite their somewhat fragmentary nature, these new observations provide a valuable database on the (3)Pi(u) states of N(2) and their interactions which will help elucidate the predissociation mechanisms for the nitrogen molecule.
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Affiliation(s)
- B R Lewis
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia.
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Stark G, Lewis BR, Heays AN, Yoshino K, Smith PL, Ito K. Oscillator strengths and line widths of dipole-allowed transitions in N214 between 89.7 and 93.5nm. J Chem Phys 2008; 128:114302. [DOI: 10.1063/1.2834933] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Wu CYR, Fung HS, Chang KY, Singh TS, Mu XL, Nee JB, Chiang SY, Judge DL. Fluorescence excitation spectra of the bΠu1, b′Σu+1, cnΠu1, and cn′Σu+1 states of N2 in the 80–100nm region. J Chem Phys 2007; 127:084314. [PMID: 17764255 DOI: 10.1063/1.2768923] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Fluorescence excitation spectra produced through photoexcitation of N(2) using synchrotron radiation in the spectral region between 80 and 100 nm have been studied. Two broadband detectors were employed to simultaneously monitor fluorescence in the 115-320 nm and 300-700 nm regions, respectively. The peaks in the vacuum ultraviolet fluorescence excitation spectra are found to correspond to excitation of absorption transitions from the ground electronic state to the b (1)Pi(u), b(') (1)Sigma(u) (+), c(n) (1)Pi(u) (with n=4-8), c(n) (') (1)Sigma(u) (+) (with n=5-9), and c(4) (')(v('))(1)Sigma(u) (+) (with v(')=0-8) states of N(2). The relative fluorescence production cross sections for the observed peaks are determined. No fluorescence has been produced through excitation of the most dominating absorption features of the b-X transition except for the (1,0), (5,0), (6,0), and (7,0) bands, in excellent agreement with recent lifetime measurements and theoretical calculations. Fluorescence peaks, which correlate with the long vibrational progressions of the c(4) (') (1)Sigma(u) (+) (with v(')=0-8) and the b(') (1)Sigma(u) (+) (with v(') up to 19), have been observed. The present results provide important information for further unraveling of complicated and intriguing interactions among the excited electronic states of N(2). Furthermore, solar photon excitation of N(2) leading to the production of c(4) (')(0) may provide useful data required for evaluating and analyzing dayglow models relevant to the interpretation of c(4) (')(0) in the atmospheres of Earth, Jupiter, Saturn, Titan, and Triton.
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Affiliation(s)
- C Y Robert Wu
- Space Sciences Center, University of Southern California, Los Angeles, California 90089-1341, USA.
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Haverd VE, Lewis BR, Gibson ST, Stark G. Rotational effects in the band oscillator strengths and predissociation linewidths for the lowest Πu1–XΣg+1 transitions of N2. J Chem Phys 2005; 123:214304. [PMID: 16356045 DOI: 10.1063/1.2134704] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
A coupled-channel Schrodinger equation (CSE) model of N2 photodissociation, which includes the effects of all interactions between the b, c, and o 1Pi u and the C and C' 3Pi u states, is employed to study the effects of rotation on the lowest-upsilon 1Pi u-X 1Sigmag+(upsilon,0) band oscillator strengths and 1Pi u predissociation linewidths. Significant rotational dependences are found which are in excellent agreement with recent experimental results, where comparisons are possible. New extreme-ultraviolet (EUV) photoabsorption spectra of the key b 1Pi u<--X 1Sigmag +(3,0) transition of N2 are also presented and analyzed, revealing a b(upsilon=3) predissociation linewidth peaking near J=11. This behavior can be reproduced only if the triplet structure of the C state is included explicitly in the CSE-model calculations, with a spin-orbit constant A approximately 15 cm(-1) for the diffuse C(upsilon=9) level which accidentally predissociates b(upsilon=3). The complex rotational behavior of the b-X(3,0) and other bands may be an important component in the modeling of EUV transmission through nitrogen-rich planetary atmospheres.
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Affiliation(s)
- V E Haverd
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
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Stark G, Huber KP, Yoshino K, Smith PL, Ito K. Oscillator strength and linewidth measurements of dipole-allowed transitions in N214 between 93.5 and 99.5nm. J Chem Phys 2005; 123:214303. [PMID: 16356044 DOI: 10.1063/1.2134703] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Line oscillator strengths in 16 electric dipole-allowed bands of 14N2 in the 93.5-99.5 nm (106,950-100,500 cm(-1)) region have been measured at an instrumental resolution of 6.5 x 10(-4) nm (0.7 cm(-1)). The transitions terminate on vibrational levels of the 3psigma 1Sigma u (+), 3ppi 1Pi u, and 3ssigma 1Pi u Rydberg states and of the b' 1Sigma u (+) and b 1Pi u valence states. The J dependences of band f values derived from the experimental line f values are reported as polynomials in J'(J'+1) and are extrapolated to J'=0 in order to facilitate comparisons with results of coupled-Schrodinger-equation calculations that do not take into account rotational interactions. Most bands in this study reveal a marked J dependence of the f values and/or display anomalous P-, Q- and R-branch intensity patterns. These patterns should help inform future spectroscopic models that incorporate rotational effects, and these are critical for the construction of realistic atmospheric radiative transfer models. Linewidth measurements are reported for four bands. Information provided by the J dependences of the experimental linewidths should be of use in the development of a more complete understanding of the predissociation mechanisms in N2.
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Affiliation(s)
- G Stark
- Department of Physics, Wellesley College, Wellesley, Massachusetts 02481, USA.
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Sprengers JP, Ubachs W, Baldwin KGH. Isotopic variation of experimental lifetimes for the lowest Πu1 states of N2. J Chem Phys 2005; 122:144301. [PMID: 15847517 DOI: 10.1063/1.1869985] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Lifetimes of several (1)Pi(u) states of the three natural isotopomers of molecular nitrogen, (14)N(2), (14)N(15)N, and (15)N(2), are determined via linewidth measurements in the frequency domain. Extreme ultraviolet (XUV)+UV two-photon ionization spectra of the b (1)Pi(u)(v=0-1,5-7) and c(3) (1)Pi(u)(v=0) states of (14)N(2), b (1)Pi(u)(v=0-1,5-6) and c(3) (1)Pi(u)(v=0) states of (14)N(15)N, and b (1)Pi(u)(v=0-7), c(3) (1)Pi(u)(v=0), and o (1)Pi(u)(v=0) states of (15)N(2) are recorded at ultrahigh resolution, using a narrow band tunable XUV-laser source. Lifetimes are derived from the linewidths of single rotationally resolved spectral lines after deconvolution of the instrument function. The observed lifetimes depend on the vibrational quantum number and are found to be strongly isotope dependent.
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Affiliation(s)
- J P Sprengers
- Department of Physics and Astronomy, Laser Centre, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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Lewis BR, Gibson ST, Zhang W, Lefebvre-Brion H, Robbe JM. Predissociation mechanism for the lowest 1 Pi u states of N2. J Chem Phys 2005; 122:144302. [PMID: 15847518 DOI: 10.1063/1.1869986] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Separate coupled-channel Schrödinger-equation (CSE) models of the interacting (1)Pi(u) (b,c,o) and (3)Pi(u) (C,C(')) states of N(2) are combined, through the inclusion of spin-orbit interactions, to produce a five-channel CSE model of the N(2) predissociation. Comparison of the model calculations with an experimental database, consisting principally of detailed new measurements of the vibrational and isotopic dependence of the (1)Pi(u) linewidths and lifetimes, provides convincing evidence that the predissociation of the lowest (1)Pi(u) levels in N(2) is primarily an indirect process, involving spin-orbit coupling between the b (1)Pi(u)- and C (3)Pi(u)-state levels, the latter levels themselves heavily predissociated electrostatically by the C(') (3)Pi(u) continuum. The well-known large width of the b(v=3) level in (14)N(2) is caused by an accidental degeneracy with C(v=9). This CSE model provides the first quantitative explanation of the predissociation mechanism for the dipole-accessible (1)Pi(u) states of N(2), and is thus likely to prove useful in the construction of realistic radiative-transfer and photochemical models for nitrogen-rich planetary atmospheres.
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Affiliation(s)
- B R Lewis
- Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
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