Variational Calculations of Rovibrational Energies for CO(2)

In this work, the BaI D(2)Sigma(+) and G(2)Sigma(+) electronic states were investigated using laser-induced fluorescence (LIF) and Fourier transform spectroscopy (FTS). The LIF visible spectra were obtained by using the second harmonic of the Ti:sapphire single-mode laser and the Ar(+) and Kr(+) multimode lasers as excitation sources. Previously recorded data, taken from C. A. Leach, A. A. Tsekouras, and R. N. Zare (1992, J. Mol. Spectrosc. 153, 59-72) and from R. F. Gutterres, J. Vergès, and C. Amiot (1999, J. Mol. Spectrosc. 196, 29-44; 2000, J. Mol. Spectrosc. 200, 253-260; and 2000, J. Mol. Spectrosc. 201, 326-327) were combined with the present data. Accurate and improved molecular constants for the X(2)Sigma(+), B(2)Sigma(+), A('2)Delta, A(2)Pi, C(2)Pi, and D(2)Sigma(+) states and 16 term values of the G(2)Sigma(+) state were derived from a simultaneous treatment of the whole data set (12 684 transitions) with a standard deviation of 3.26x10(-3) cm(-1). Copyright 2001 Academic Press.     

Fourier Transform Spectroscopy of the A'(1)Pi-X(1)Sigma(+) System of CaO

The A'(1)Pi-X(1)Sigma(+) near-infrared system of CaO was observed for the first time at high resolution using a Fourier transform spectrometer. The A'(1)Pi-X(1)Sigma(+) chemiluminescence was excited in a Ca + N(2)O flame produced in a Broida-type oven. More than 3000 rotational lines, classified into 19 bands involving the A'(1)Pi 0 /= 2) levels with the nearby b(3)Sigma(+) (v-2) levels has been detected. An extended set of A'(1)Pi (v = 0-3) data has been obtained which is suitable for use in a future multistate deperturbation analysis of the a(3)Pi approximately A'(1)Pi approximately b(3)Sigma(+) approximately A(1)Sigma(+) complex of excited states. The new near-infrared spectra of the A'(1)Pi-X(1)Sigma(+) transition of CaO also permits the first direct high-resolution linkage between the orange and green systems and the near-infrared bands. Copyright 2000 Academic Press.     

The (1)(3)Pi Electronic State of LaF

Rotational studies of bands of the infrared systems (1)(3)Pi-->(1)(3)Delta and (1)(3)Pi(1)-->X(1)Sigma(+) of lanthanum monofluoride were carried out with the aim of characterizing the (1)(3)Pi state, assuming the previous representations of X(1)Sigma(+) and (1)(3)Delta (1-3). The vibrational levels of (1)(3)Pi involved in the analyzed transitions were v=0, 1, 2 of the Omega=0 component, v=0, 1 of the Omega=1 component, and v=0 of the Omega=2 component. Perturbations were observed in both systems which were ascribed to spin-uncoupling interactions between (1)(3)Pi(2)(v=0) and (1)(3)Pi(1)(v=1) levels. A 9x9 matrix representation at equilibrium of the complex of interacting levels (v=0, 1, 2) was constructed, each diagonal v-block corresponding to a triplet model of the rovibrational (3)Pi Hamiltonian. The wavenumbers of some 1910 lines in the two systems were simultaneously fitted (rms error of the fit of about 0.0053 cm(-1)), thus yielding a consistent set of accurate spectroscopic constants for the (1)(3)Pi state; the spin-uncoupling interaction parameter was determined as B(Pi)(0, 1)=0.010917(13) cm(-1). Copyright 2001 Academic Press.     

The Rotational Spectrum of SO(2) and the Determination of the Hyperfine Constants and Nuclear Magnetic Shielding Tensors of (33)SO(2) and SO(17)O

Rotational analyses of the B(2)Sigma(+)(u) --> X(2)Sigma(+)(g) system of the (14)N(+)(2) molecule have been extended to include the vibrational levels up to v' = 4. Spectral data from 20 bands obtained from high-resolution Fourier transform spectrometry of a hollow-cathode and a Pointolite lamp were included in the analysis. A global deperturbation yielded molecular parameters of the highly perturbed B(2)Sigma state and interaction parameters A(2)Pi(u) approximately B(2)Sigma(u) with a standard deviation of 0.011 cm(-1). Rotational term values of the B(2)Sigma(+) state were also determined. New perturbations in the B(2)Sigma(+) (v = 0) level have been observed at N approximately 85 and N approximately 96. Copyright 2000 Academic Press.     

High-Resolution Fourier Transform Emission Spectroscopy of the B(2)Sigma(+) (v = 0)-X(2)Sigma(+) (v = 0) Transition of the PN(+) Ion

Ultraviolet emission spectrum of the B(2)Sigma(+) (v = 0)-X(2)Sigma(+) (v = 0) transition of the PN(+) ion has been observed at a resolution of 0.05 cm(-1) by a Fourier transform spectrometer. The rotational analysis led to a great improvement of rotational constants in the B(2)Sigma(+) (v = 0) and X(2)Sigma(+) (v = 0) states as well as to the first determination of centrifugal distortion constants for both levels and spin-rotation interaction constant in the X(2)Sigma(+) (v = 0) state. Rotational perturbation in the B(2)Sigma(+) (v = 0) state was observed. Copyright 2000 Academic Press.     

High-Resolution Study of the BaI A(2)Pi Electronic State

Near-infrared and visible spectra of the A(2)Pi-X(2)Sigma(+), C(2)Pi(1/2)-A(2)Pi(1/2), C(2)Pi(1/2)-B(2)Sigma(+), and C(2)Pi(1/2)-X(2)Sigma(+) band systems of the BaI molecule were recorded by using Fourier transform spectroscopy (FTS). The spectra were produced from the chemiluminescent reaction Ba + I(2) and also by using laser-induced fluorescence (LIF) technique in which the laser sources were a Ti:sapphire single-mode laser, a dye single-mode laser, and a Kr(+) multimode ion laser. Resolved rotational data, originating from 19 vibrational levels (0 相似文献   

Laser-Induced Fluorescence and Fourier Transform Spectroscopy of NiCl: Identification of a Low-Lying (2)Sigma(+) State (1768 cm(-1))

From a comparison with the spectrum of NiF, a low-lying (2)Sigma(+) state is expected to lie in the first 2000 cm(-1) above the ground X(2)Pi(3/2) state of NiCl. The identification of this (2)Sigma(+) (v = 0) state (at 1768 cm(-1)) has been carried out through the analysis of two electronic transitions (2)Pi(3/2)-(2)Sigma(+) (22 720 cm(-1)) and (2)Pi(1/2)-(2)Sigma(+) (23 210 cm(-1)) recorded by high-resolution Fourier transform spectroscopy. Dispersed fluorescence spectroscopy allowed these transitions to be located on an absolute energy-level diagram that includes the previously studied electronic states. Copyright 2000 Academic Press.     

Characterization of the Ground State of Br(2) by Laser-Induced Fluorescence Fourier Transform Spectroscopy of the B(3)Pi(0(+))(u)-X(1)Sigma(+)(g) System

The laser-induced fluorescence (LIF) spectrum of the B(3)Pi(0(+))(u)-X(1)Sigma(+)(g) system of Br(2) was recorded by Fourier transform spectroscopy (FTS). The LIF spectra were obtained by using continuous-wave dye laser excitation in the spectral region 16 800-18 000 cm(-1). About 1800 rotationally resolved lines were recorded in 96 fluorescence progressions, originating from the 10 相似文献   

Fourier Transform Emission Spectroscopy of the Low-Lying Electronic States of NbN

The high-resolution spectrum of NbN has been investigated in emission in the 3000-15 000 cm(-1) region using a Fourier transform spectrometer. The bands were excited in a microwave discharge through a mixture of NbCl(5) vapor, approximately 5 mTorr of N(2), and 3 Torr of He. Numerous bands observed in the near-infrared region have been classified into the following transitions: f(1)Phi-c(1)Gamma, e(1)Pi-a(1)Delta, C(3)Pi(0+)-A(3)Sigma(-)(1), C(3)Pi(0-)-A(3)Sigma(-)(1), C(3)Pi(1)-a(1)Delta, C(3)Pi(1)-A(3)Sigma(-)(0), d(1)Sigma(+)-A(3)Sigma(-)(0), and d(1)Sigma(+)-b(1)Sigma(+). These observations are consistent with the energy level diagram provided by laser excitation and emission spectroscopy [Y. Azuma, G. Huang, M. P. J. Lyne, A. J. Merer, and V. I. Srdanov, J. Chem. Phys. 100, 4138-4155 (1993)]. The missing d(1)Sigma(+) state has been observed for the first time and its spectroscopic parameters are consistent with the theoretical predictions of S. R. Langhoff and W. Bauschlicher, Jr. [J. Mol. Spectrosc. 143, 169-179 (1990)]. Rotational analysis of a number of bands has been obtained and improved spectroscopic parameters have been extracted for the low-lying electronic states. The observation of several vibrational bands with v = 1 has enabled us to determine the vibrational intervals and equilibrium bond lengths for the A(3)Sigma(-)(0), a(1)Delta, b(1)Sigma(+), d(1)Sigma(+), and C(3)Pi(1) states. Copyright 2000 Academic Press.     

Submillimeter-Wave Spectroscopy of CO in the a(3)Pi State

Submillimeter-wave absorption spectrum of CO in electronically excited a(3)Pi state was observed in the 540-830 GHz region by using a phase-locked BWO spectrometer. New rotational transitions up to J = 9-8 in the vibrational excited states up to v = 5 were analyzed accompanied with previous observations in the RF and millimeter-wave regions. A multivibrational states fit among a' (3)Sigma(+) (v = 0-3) and a(3)Pi (v = 0-7) states was performed in order to analyze overall perturbation between the a(3)Pi and a' (3)Sigma(+) states. As a result, the deperturbed rotational parameters were derived precisely to improve the RKR potential. Copyright 2000 Academic Press.     

The E(2)Sigma(+) --> C(2)Pi Transition of NO and Term Values for the A, D, E, and C Lowest Rydberg Levels

The E(2)Sigma(+) --> C(2)Pi Rydberg-Rydberg transition of (14)N(16)O near 8492 cm(-1) has been studied by Fourier transform spectrometry in the emission from a dc excited supersonic jet expansion and from a dc discharge under equilibrium conditions. The same transition has also been observed in laser-induced stimulated emission. Line wavenumbers of the 0-0, 1-1, and 2-2 bands, together with data for previously published near-infrared transitions, have been reduced to consistent sets of rovibronic term values for v = 0, 1, and 2 of the A(2)Sigma(+), D(2)Sigma(+), E(2)Sigma(+), and C(2)Pi states which frequently serve as intermediates in the multiphoton excitation of higher Rydberg levels of NO. Copyright 2000 Academic Press.     

The Perturbation between the G(1)Pi(g) and 2(1)Delta(g) States of (7)Li(2)

We have observed the rotational levels in the v = 2, 3, 5, 6, 7, and 8 vibrational manifolds of the 2(1)Delta(g) state of (7)Li(2) via the A(1)Sigma(+)(u) intermediate levels by DeltaLambda = 2 transitions. This violation of the DeltaLambda = 0, +/-1 selection rule is due to the interaction with the G(1)Pi(g) state. Band-by-band deperturbations of the G(1)Pi(g) approximately 2(1)Delta(g) (v(Pi), v(Delta)) = (11, 2), (12, 3), (15, 5), (16, 6), (18, 7), and (19, 8) bands have been performed. Deperturbed molecular constants and rotational-electronic interaction parameters are reported here. Copyright 2000 Academic Press.     

Analysis of the 1-v" Progression of the 3A Band System (c(3)Pi-a(3)Pi) in the (13)C(16)O Molecule Spectrum

The 1-0, 1-1, and 1-2 bands of the 3A system of (13)CO (c(3)Pi-a(3)Pi) have been recorded for the first time, in the form of discharge emission spectra photographed at high resolution. Preliminary rotational analysis suggests that the v = 1 level of the c(3)Pi state is perturbed in a fashion similar to the v = 0 level, previously observed by Dabrowski et al. (1987. I. Dabrowski, M. Vervolet, and D. C. Wang, Can. J. Phys. 65, 1171-1177). Rotational combination differences from the 1720 measured lines have been used to obtain rotational constants for the v = 0-2 levels of the a(3)Pi state, using the Hamiltonian of Brown et al. (1979. J. M. Brown, E. A. Calbourn, J. K. G. Watson, and F. D. Wayne, J. Mol. Spectrosc. 74, 294-318). and the least squares formalism of Curl and Dane (1988. J. Mol. Spectrosc. 128, 406-412), as modified by Watson (1989. J. Mol. Spectrosc. 138, 302-308). Term values for the c(3)Pi, v = 1 level have then been obtained from the line frequencies, and a set of effective rotational constants for the c(3)Pi (v = 1) level of (13)CO has been derived. Copyright 2000 Academic Press.     

Enhanced Access to the Dark Triplet States of (7)Li(2) through New Singlet-Triplet A(1)Sigma(+)(u) approximately b(3)Pi(u) Perturbation Window Levels: Perturbation-Facilitated Optical-Optical Double Resonance Study of the 2(3)Sigma(+)(g) State

Two new pairs of singlet-triplet A(1)Sigma(+)(u) approximately b(3)Pi(u) mixed levels of (7)Li(2) have been observed and used here as "window" levels in cw perturbation-facilitated optical-optical double-resonance (PFOODR) experiments. Previously, only one b(3)Pi(u) vibrational level, v = 19, was known to mix with the singlet A(1)Sigma(+)(u) v = 13 level, resulting in three perturbed A approximately b pairs [L. Li, T. An, T.-J. Whang, A. M. Lyyra, W. C. Stwalley, R. W. Field, and R. A. Bernheim, J. Chem. Phys. 96, 3342 (1992)]. The scarcity of window levels and the resulting difficulty in accessing the dark triplet states of Li(2) is caused by the weak spin-orbit interaction of Li(2). The two new mixed b(3)Pi(u) v = 15 and 22 levels reported here enhance access to the dark triplet state manifold through expansion of the Franck-Condon overlap factor range. Furthermore, the earlier range of accessible rotational levels, N = 5, 7, and 10, is now expanded to include N = 8 and N = 16, thereby allowing for more reliable determination of the excited triplet states rotational structure. To demonstrate the importance of the new A(1)Sigma(+)(u) approximately b(3)Pi(u) mixed levels, we have studied the 2(3)Sigma(+)(g) state by cw PFOODR fluorescence excitation spectroscopy. New molecular constants and RKR potential curve have been determined. As previously reported [L. Li, G. Lazarov, and A. M. Lyyra, J. Mol. Spectrosc. 191, 387 (1998)], the 2(3)Sigma(+)(g) state interacts with the repulsive 1(3)Pi(g) state by L-uncoupling and predissociates. We show that some 2(3)Pi(g) levels predissociate accidentally by the 1(3)Pi(g) state via the 2(3)Sigma(+)(g) state through L-uncoupling. Copyright 2001 Academic Press.     

Anomalous Vibrational Dependence of the Rotational and Hyperfine Parameters in the B(4)Pi-X(4)Sigma(-) Transition of NbO

The laser excitation spectrum of jet-cooled NbO in the region 16 000-18 000 cm(-1) has been recorded at high resolution, giving rotational and hyperfine constants for the levels v=0-3 of the B(4)Pi state and v=1 of the X(4)Sigma(-) state; zero gaps have also been measured at low resolution for some weaker bands involving higher vibrational levels. Taken together with the laser data for the B-X (0,0) band from Adam et al. (J. Chem. Phys. 94, 6240-6262 (1994)) and the Fourier transform emission data for the doublet manifold from Launila et al. (J. Mol. Spectrosc. 186, 131-143 (1997)), the new data give a very complete picture of the vibrational energy level pattern in this region. Strong irregularities in the vibrational dependences of the B(4)Pi rotational and hyperfine constants can be interpreted in terms of spin-orbit interaction between the B(4)Pi state and the f(2)Pi, e(2)Phi, and d(2)Delta states. The interaction is strong enough that all three doublet states can be seen in absorption from the X(4)Sigma(-) ground state, adding to the complexity of the spectrum. The hitherto unknown sigmadeltasigma* (4)Delta state is estimated to lie near 17 500 cm(-1), from the change of sign in the spin-rotation parameter gamma of the B(4)Pi state between v=2 and 3. Copyright 2001 Academic Press.     

High-Resolution, Rotationally Resolved Electronic Spectroscopy of the MgNC Radical

High-resolution, rotationally resolved, laser-induced fluorescence (LIF) spectra for the origin band, as well as several transitions involving vibrationally excited levels of the ?2Pi <-- &Xtilde2Sigma+ electronic transition of the MgNC radical, have been recorded using the output of a pulse-amplified Ti:Sapphire ring laser. The MgNC radical was generated in a supersonic free jet expansion by simultaneous laser ablation of a magnesium rod and photolysis of acetonitrile (CH3CN). Rotational analysis yielded molecular constants for both the ground and excited states of the studied vibronic transitions. The molecular constants for the vibrationless state of the &Xtilde state are in excellent agreement with previous microwave studies of MgNC. Since the ? electronic state of MgNC is a linear 2Pi state, the bending vibronic level structure is subject to both Renner-Teller and spin-orbit coupling. Suggested vibronic assignments of the observed transitions, made considering both these interactions and with the aid of the rotational analysis, are discussed. Copyright 1999 Academic Press.     

The Rotational Analysis of the A(2)Pi(r)-X(2)Sigma(+) Band System of MgBr

The A(2)Pi(r)-X(2)Sigma(+) emission spectrum of the magnesium monobromide radical, MgBr, has been recorded with a Fourier transform spectrometer modified to record double-sided interferograms. The emission spectra of the Deltav = -2, -1, 0, +1 bands were generated in a microwave discharge of a mixture of argon and vaporized MgBr(2). The Deltav = 0 and -1 bands were rotationally resolved, but the F(2) spin component (A(2)Pi(3/2)) in the (1, 1), (1, 2) and vibrational bands with v' > 1 were missing in our spectra because of a strong predissociation in the A state. The molecular constants in both electronic states were determined for the two bromine isotopomers. The r(0) bond length in the A state is about 2.327 ?, which is about 0.02 ? shorter than in the ground state. Franck-Condon factors were calculated from the Rydberg-Klein-Rees potentials, and they reproduce the observed relative intensities of the bandheads. An upper limit for the dissociation energy (D(0)(0)) was obtained as 26 268.4 cm(-1), based on the absence of the energy level with v = 1, A(2)Pi(3/2), J = 1.5 in our spectrum. Copyright 2000 Academic Press.     

激光冷却SH~–阴离子的理论研究

本文采用多组态相互作用及Davidson修正方法和全电子基组计算了SH~-阴离子的X~1∑~+,a~3∏和A~1∏态的势能曲线、电偶极矩和跃迁偶极矩.计算的光谱常数与实验值及已有的理论值符合得很好.在计算中考虑了自旋-轨道耦合效应.计算得到a~3∏_1(v'=0)?X~1∑_(0+)~+(v"=0)和A~1∏_1(v'=0)?X~1Σ_(0+)~+(v"=0)跃迁具有高对角分布的弗兰克-康登因子,分别为0.9990和0.9999;计算得到a~3∏_1和A~1∏_1态的自发辐射寿命分别为1.472和0.188 ms.A~1∏_1?X~1∑_(0+)~+跃迁存在中间态a~3∏_(0+)和a~3∏_1,但中间态对激光冷却SH~-阴离子的影响可以忽略.分别利用a~3∏_1(v'=0)? X~1∑_(0+)~+(v"=0)和A~1∏_1(v'=0)? X~1∑_(0+)~+(v"=0)跃迁构建了准闭合的能级系统,冷却所需的激光波长分别为492.27和478.57 nm.最后预测了激光冷却SH~-阴离子能达到的多普勒温度和反冲温度.这些结果为进一步实验提供了理论参数.     

Spectroscopic study of B2Σ+–X1 2Π1/2 transition of electron electric dipole moment candidate PbF

PbF, a valuable candidate for measuring the electron electric dipole moment (eEDM), is of great significance in measuring its spectrum and deriving its molecular constants in experiment. In the present work, the rovibronic spectrum of the B$^{2}{\Sigma }^{+}$-X$_{1}^{\, 2}{\Pi }_{1/2}$ transition of PbF in a wavelength range of 260 nm-285 nm is studied by the laser ablation/laser induced fluorescence method. The molecular parameters of the X$_{1}^{\, 2}{\Pi }_{1/2}$ (${v'}=0)$ and B$^{2}{\Sigma }^{+}$ (${v}'=0, 1$) states are derived from the recorded spectra of the (0, 0) and (1, 0) bands of the B$^{2}{\Sigma }^{+}$-X$_{1}^{\, 2}{\Pi }_{1/2}$ transition. Also, the Franck-Condon factors (FCFs) of the transitions between the B$^{2}{\Sigma }^{+}$ and X$_{1}^{\, 2}{\Pi }_{1/2}$ states are calculated by the RKR/LEVEL method and the Morse potential method, respectively.     

The A (3Pi1) State of ClF

The A(3Pi1) state of ClF is studied (1) in emission from the beta(1(3)P2) ion-pair state in a high-pressure discharge, (2) from its role in perturbations of the B(3Pi0(+)) and A'(3Pi2) states, and (3) in direct absorption from the X(1Sigma+) ground state. The last of these is obtained via a UV-labeling technique and represents the first observation of the A <-- X transition. The emission spectrum yields extensive assignments for the 0-4, 0-5, and 1-4 bands of beta --> A, with both e and f lines identified. The well-known perturbation in v = 7 of the B state is attributed to interaction with v = 9 of A. A newly identified perturbation in B(6) involves coupling with A(8). The known perturbation in B(8) may involve A(11), but other assignments cannot be ruled out. Approximate potential curves are derived for all three valence states and used to compute the vibrational factors for the perturbations, permitting extraction of the electronic coupling strengths. The B-A coupling elements are within approximately 10% of expectations for rotation-electronic coupling within a Hund's case (a) 3Pi manifold, but the strength of the perturbation between A(5) and A'(6) is only about 30% of predictions for this model. Copyright 1999 Academic Press.