Resonance-enhanced multiphoton ionization of NO via X~2II-A~2Σ transition

The resonance-enhanced multiphoton ionization (REMPI) spectrum of NO has been obtained in the range of 420 - 480 nm with a Nd:YAG pumped optical parametric generator and amplifier. The spectral lines can be attributed to NO X2II(v=0,1)-A2(v' = 0,1) transitions. In this wavelength range, NO molecules are ionized via the resonant intermediate state A2E+ and by a (2 + 2) REMPI process. The dependence of ion signals on laser intensity and gas pressure is discussed. The variation of the ionization signal versus laser intensity is near quartic. This is in good agreement with theory.     

Resonance-enhanced multiphoton ionization of NO via X2П→A2∑ transition

The resonance-enhanced multiphoton ionization (REMPI) spectrum of NO has been obtained in the range of 420-480 nm with a Nd:YAG pumped optical parametric generator and amplifier. The spectral linescan be attributed to NO X2П(v" = 0, 1) → A2∑(v' = 0, 1) transitions. In this wavelength range, NO molecules are ionized via the resonant intermediate state A2∑+ and by a (2 + 2) REMPI process. The dependence of ion signals on laser intensity and gas pressure is discussed. The variation of the ionization signal versus laser intensity is near quartic. This is in good agreement with theory.     

Fourier spectroscopy of the Asundi system (a′3Σ+-a3Π) of 13C16O

The Asundi system (a′³Σ⁺-a³Π) of ¹³C¹⁶O has been studied between 3500 and 12 000 cm⁻¹ by high-resolution Fourier transform spectroscopy. The 10 bands, 0-0, 0−1, 1−0, 1−1, 1−2, 2−0, 2−1, 3−0, 4−0, and 4−2, were analyzed taking into account the strong perturbations appearing in the a′³Σ⁺ (v = 0,…,4) levels. Accurate perturbation parameters were obtained for all interacting states.     

A tentative multiphoton ionization of CS2 molecule: Spectroscopy of Ã2πu state of CS 2 + ion

The spectroscopic study of excited molecular cationCS ₂ ⁺ (òπ_u ) by a different method is presented. In this technique the decay of excited states is monitored by measuring the photons emitted. The peaks in the photon spectrum would correspond to the energy levels of the ion. The vibrational-vibrational, vibrational-electronic interactions have been observed. Symmetry forbidden excitation of one quantum of bending vibration is observed which gives unperturbed value for the bending vibration. The Renner-Teller splitting for the δ_g and Σ _g ^- components of the bending mode (v ₂ ^′ = 1) in the upper excited òπ_u state has been observed. A tentative vibrational analysis of the Ã→ X system has been made.     

Characterization of the [Xtilde] 1Σ+ à 3Π and à 1Π electronic states of BBO

The three lowest-lying electronic states, [Xtilde] ¹Σ⁺, à ³II and à ¹II, of the linear BBO molecule have been systematically investigated using ab initio electronic structure theory. The equilibrium structures and physical properties including dipole moments, vibrational frequencies and associated infrared intensities, Renner parameters and energetics for the three states of BBO have been determined employing SCF, CISD, CCSD and CCSD(T) levels of theory and a wide range of basis sets. The ground state of BBO presents a degenerate real bending frequency, while the à ³II and à ¹II states show two distinct real bending frequencies due to the Renner-Teller interaction. The bending motion of the à ¹II state was analysed using the equation-of-motion (EOM)-CCSD and EOM-CC3 techniques in order to avoid possible variational collapse to a lower-lying state. The [Xtilde] ¹Σ⁺-à ³II separation was predicted to be T ₀ = 16.6 kcal mol^?1 (5800 cm^?1, 0.719 eV) at the cc-pVQZ CCSD(T) level of theory. With the cc-pVQZ EOM-CC3 method the [Xtilde] ¹Σ⁺-à ¹II splitting was predicted to be T ₀ = 48.0 kcal mol^?1 (16 800 cm^?1, 2.08 eV), which is in good agreement with the experimental value of T ⁰ = 46.6 kcal mol^?1 (16 300 cm^?1, 2.02 eV). The Renner parameters and averaged harmonic frequencies of the bending mode were determined to be ? = 0.184 and ω₂ = 363 cm^?1 for the à ³II state, and ? = 0.246 and ω₂ = 383cm^?1 for the à ¹II state. The theoretical [Xtilde] ¹Σ⁺ state harmonic B-B stretching frequency ω₃ = 636 cm^?1 is somewhat higher than the experimental estimate of 582 cm^?1 and the predicted à ¹II state harmonic B-B stretching frequency ω₃ = 861 cm^?1 is significantly higher than the experimental estimate of 440 cm^?1     

Resonance-enhanced multi-photon ionization spectrum of NO in 575-680 nm wavelength region

The multi-photon ionization spectrum of NO in the wavelength region of 575-680 nm is obtained with an optical parameter generator and amplifier (OPG/OPA) pumped by a picosecond Nd:YAG laser as radiation source. The banded structure of the spectrum indicates that NO molecule is ionized in resonant manner and the peaks of the spectrum are assigned to the transition of NO molecule from the ground electronic state to A2∑(v' = 0,1,2,3), E2∑(v' = 0,1,2), F2Δ(v' = 0,1,2,3) and H2∑(v' = 0,1,2) intermediate resonant ones. The molecule constants about NO (A2∑, E2∑, F2Δ, H2∑) states are calculated from the center wavelength of the spectrum. It is also found that owing to the special electron configuration of NO, this molecule does not follow the normal transition selection rule of the diatomic molecule during the multi-photon process.     

Analysis of two-torus in a new four-dimensional autonomous system

In this paper, we report the dynamical behaviours of a four-dimenslonal autonomous continuous dissipative system analysed when the parameter is varied in the range we are interested in. The system changes its dynamical modes between periodic motion and quasiperiodic motion. Furthermore, the existence of two-torus is investigated numerically by means of Lyapunov exponents. By taking advantage of phase portraits and Poincaré sections, two types of the two-torus are observed and proved to have the structure of ring torus and horn torus, both of which are known to be the standard tori.     

High-resolution laser excitation spectroscopy: Analysis of the B2Σ+-X2Σ+ system of CaCl

Single-mode cw dye laser excitation spectra of the (0, 0), (1, 1), and (2, 2) bands of the B²Σ⁺-X²Σ⁺ system of CaCl have been observed and assigned. Some 300 independent photo-luminescence spectra have been used in making the rotational assignment and demonstrate the power of the technique of line-by-line analysis in unraveling complex spectra. Spectroscopic constants (cm^?1) obtained from a weighted least squares fit of the data are given below. Numbers in parentheses refer to 95% confidence limits in the last digit.

     

12.

Rotational analysis of the a3Π(0+, 1) → X1Σ+ system of 11BI     

《Journal of Molecular Spectroscopy》1987,121(2):453-464

     

13.

Rotational analysis of the a3Π-X1Σ+ bands of GaD     

《Journal of Molecular Spectroscopy》1987,122(2):417-427

A new method of producing strong and clean emission spectra of the gallium hydride/deuteride molecule has been developed. Five bands belonging to the gallium deuteride molecule (GaD) have been photographed under high resolution. The rotational analyses of the bands lying at 5669.14 Å (0-0) and 5675.10 Å (1-1) in the a³Π₁-X¹Σ⁺ transition, 5761.0 Å (0-0) and 5766.20 Å (1-1) in the a³Π_0⁺-X¹Σ⁺ transition, and 5760.85 Å (0-0) in the a³Π_0⁻-X¹Σ⁺ transition have been performed. Accurate rotational constants (B, D) have been determined for the X¹Σ⁺, a³Π_0^± and a³Π_1^± states. The Λ doubling in the a³Π₀ (v = 0) and a³Π₁ (v = 0 and 1) states are obtained.     

14.

Two-colour coherent control of multiphoton ionization： a comparison between long-range and short-range potential model atoms          下载免费PDF全文

李鹏程  周效信 《中国物理》2007,16(10):2946-2951

Using the numerical solution of the time-dependent Schr\"odinger equation of a one-dimensional model atom in a two-colour laser field, we have investigated the effects of the potential models on coherent control of atomic multiphoton ionization. It is found that the photoelectron spectra are obviously different for the long-range (Coulomb-like) and short-range (with no excited bound states) potential model atoms, which are produced by two-colour coherent control of atomic multiphoton ionization in a few laser cycles. Our results indicate that two-colour coherent control of atomic multiphoton ionization can be observed in simulations, depending on the choice of the model potentials.     

15.

Rovibrational transition properties of the X1Σ+ and A1Π states of carbon monosulfide     

Wei Xing  Jinfeng Sun 《Molecular physics》2020,118(18)

Carbon monosulfide was detected in outer space by rovibrational spectroscopy of the X ¹Σ⁺ state and A ¹Π – X ¹Σ⁺ system. This work calculated the potential energy curves and dipole moment functions of the X ¹Σ⁺ ₀₊ and A ¹Π₁ states, and computed the transition dipole moments between the two states employing the CASSCF method, followed by the valence icMRCI approach. Core-valence correlation and scalar relativistic corrections were included. The extrapolation of potential energies to the complete basis set limit was performed. The spin-orbit coupling effect was included. The Einstein A coefficients, band origins, and oscillator strengths were calculated for the rovibrational transitions when J?≤?150. The rovibrational transitions of the X ¹Σ⁺ ₀₊ and A ¹Π₁ states became very weak when Δυ?≥?6. The Einstein A coefficients of vibronic emissions of the A ¹Π₁ – X ¹Σ⁺ ₀₊ system were large, indicating that the emissions were able to be measured easily through spectroscopy. Several rovibrational transitions of the A ¹Π₁ – X ¹Σ⁺ ₀₊ system were analysed in detail. The distribution of radiative lifetime varying as rotational quantum number was calculated. The results obtained in this work agree well with the available experimental values.     

16.

1+1′ resonant multiphoton ionisation of OH radicals via the A2Σ+ state: insights from direct comparison with A-X laser-induced fluorescence detection     

Joseph M. Beames  Fang Liu 《Molecular physics》2014,112(7):897-903

A 1+1′ resonance-enhanced multiphoton ionisation (REMPI) scheme for OH X²Π radicals is characterised for a broad range of intermediate A²Σ⁺ (v = 1, J, F_i) levels. The intensities of OH A-X (1,0) transitions detected by subsequent fixed-frequency VUV ionisation are compared with those obtained by near simultaneous laser-induced fluorescence (LIF) measurements. The ratios of the 1+1′ REMPI to LIF signals are used to derive enhancement factors which reflect the VUV absorption to the OH A³Π, 3d, v = 0 Rydberg state and/or the fast autoionisation process that yields OH⁺ ions. The determination of the enhancement factors permits 1+1′ REMPI to be utilised as a quantitative state-specific probe of OH X²Π radicals.     

17.

The high-resolution emission spectrum of S2 in the near infrared: The b1Σg+-X3Σg− system     

《Journal of Molecular Spectroscopy》1986,119(2):377-387

     

18.

Intensity anomaly in the A2∑+←X2∏ resonant-(2+2) multiphoton ionization spectra of NO     

Shi Zhouzheng  Lu Chengzai  Xia Jingfang  Li Yufen 《Applied physics. B, Lasers and optics》1988,47(1):97-100

The two-photon resonant four-photon ionization spectra of NO via A²⁺X² (v=0,1) states have been measured. Some intensity-anomalous lines have been found. Based on the signal-power dependence measurement for the normal and anomalous lines, a double resonance and collision ionization model is suggested to elucidate the intensity anomaly.     

19.

Temperature sensitivity of molecular oxygen resonant-enhanced multiphoton ionization spectra involving the C3Πg intermediate state     

Yue Wu  Zhili Zhang  Steven F. Adams 《Applied physics. B, Lasers and optics》2016,122(5):149

     

20.

Rotational band contour analysis in the 2760 Å system of p-chlorofluorobenzene     

T. Cvitaš  J.M. Hollas 《Molecular physics》2013,111(2):261-269

The origin band of the 2760 å system of p-chlorofluorobenzene has been shown to be a type B band of a prolate asymmetric top. The electronic assignment of the system is therefore ¹ B ₂-¹ A ₁.

The excited state rotational constants are:

compared with the estimated ground state constants:

The rotational origin of the band is at 36275·1 ± 0·2 cm^-1.     

	$\text{X}{}^2\text{Σ}{}^{\mathrm{+}}$	$\text{B}{}^2\text{Σ}{}^{\mathrm{+}}$
$\text{T}{}_{\mathrm{e}}$	0	16856.69(2)
$\text{ω}{}_{\mathrm{e}}$	369.8(10)	366.8(10)
$\text{ω}{}_{\mathrm{e}}\text{x}{}_{\mathrm{e}}$	1.13(20)	1.28(20)
$\text{B}{}_{\mathrm{e}}$	0.15200(54)	0.15448(54)
$\text{α}{}_{\mathrm{e}}$	0.00063(34)	0.00073(35)
$\text{D}{}_{\mathrm{e}}$	1.027(16) × 10?7	1.097(17) × 10?7
$\text{γ}{}_{\mathrm{e}}$ (spin-rotation)	+0.003	?0.0630(16)

Rotational analysis of the a3Π-X1Σ+ bands of GaD

A new method of producing strong and clean emission spectra of the gallium hydride/deuteride molecule has been developed. Five bands belonging to the gallium deuteride molecule (GaD) have been photographed under high resolution. The rotational analyses of the bands lying at 5669.14 Å (0-0) and 5675.10 Å (1-1) in the a³Π₁-X¹Σ⁺ transition, 5761.0 Å (0-0) and 5766.20 Å (1-1) in the a³Π_0⁺-X¹Σ⁺ transition, and 5760.85 Å (0-0) in the a³Π_0⁻-X¹Σ⁺ transition have been performed. Accurate rotational constants (B, D) have been determined for the X¹Σ⁺, a³Π_0^± and a³Π_1^± states. The Λ doubling in the a³Π₀ (v = 0) and a³Π₁ (v = 0 and 1) states are obtained.     

Two-colour coherent control of multiphoton ionization： a comparison between long-range and short-range potential model atoms

Using the numerical solution of the time-dependent Schr\"odinger equation of a one-dimensional model atom in a two-colour laser field, we have investigated the effects of the potential models on coherent control of atomic multiphoton ionization. It is found that the photoelectron spectra are obviously different for the long-range (Coulomb-like) and short-range (with no excited bound states) potential model atoms, which are produced by two-colour coherent control of atomic multiphoton ionization in a few laser cycles. Our results indicate that two-colour coherent control of atomic multiphoton ionization can be observed in simulations, depending on the choice of the model potentials.     

Rovibrational transition properties of the X1Σ+ and A1Π states of carbon monosulfide

Carbon monosulfide was detected in outer space by rovibrational spectroscopy of the X ¹Σ⁺ state and A ¹Π – X ¹Σ⁺ system. This work calculated the potential energy curves and dipole moment functions of the X ¹Σ⁺ ₀₊ and A ¹Π₁ states, and computed the transition dipole moments between the two states employing the CASSCF method, followed by the valence icMRCI approach. Core-valence correlation and scalar relativistic corrections were included. The extrapolation of potential energies to the complete basis set limit was performed. The spin-orbit coupling effect was included. The Einstein A coefficients, band origins, and oscillator strengths were calculated for the rovibrational transitions when J?≤?150. The rovibrational transitions of the X ¹Σ⁺ ₀₊ and A ¹Π₁ states became very weak when Δυ?≥?6. The Einstein A coefficients of vibronic emissions of the A ¹Π₁ – X ¹Σ⁺ ₀₊ system were large, indicating that the emissions were able to be measured easily through spectroscopy. Several rovibrational transitions of the A ¹Π₁ – X ¹Σ⁺ ₀₊ system were analysed in detail. The distribution of radiative lifetime varying as rotational quantum number was calculated. The results obtained in this work agree well with the available experimental values.     

1+1′ resonant multiphoton ionisation of OH radicals via the A2Σ+ state: insights from direct comparison with A-X laser-induced fluorescence detection

A 1+1′ resonance-enhanced multiphoton ionisation (REMPI) scheme for OH X²Π radicals is characterised for a broad range of intermediate A²Σ⁺ (v = 1, J, F_i) levels. The intensities of OH A-X (1,0) transitions detected by subsequent fixed-frequency VUV ionisation are compared with those obtained by near simultaneous laser-induced fluorescence (LIF) measurements. The ratios of the 1+1′ REMPI to LIF signals are used to derive enhancement factors which reflect the VUV absorption to the OH A³Π, 3d, v = 0 Rydberg state and/or the fast autoionisation process that yields OH⁺ ions. The determination of the enhancement factors permits 1+1′ REMPI to be utilised as a quantitative state-specific probe of OH X²Π radicals.     

Intensity anomaly in the A2∑+←X2∏ resonant-(2+2) multiphoton ionization spectra of NO

The two-photon resonant four-photon ionization spectra of NO via A²⁺X² (v=0,1) states have been measured. Some intensity-anomalous lines have been found. Based on the signal-power dependence measurement for the normal and anomalous lines, a double resonance and collision ionization model is suggested to elucidate the intensity anomaly.     

Rotational band contour analysis in the 2760 Å system of p-chlorofluorobenzene

The origin band of the 2760 å system of p-chlorofluorobenzene has been shown to be a type B band of a prolate asymmetric top. The electronic assignment of the system is therefore ¹ B ₂-¹ A ₁.

The excited state rotational constants are:

compared with the estimated ground state constants:

The rotational origin of the band is at 36275·1 ± 0·2 cm^-1.