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 KRb (2)(3)Sigma(+) Electronic State

High-resolution spectra of the (3)(1)Pi --> (2)(3)Sigma(+) system of the KRb molecule, obtained after excitation with fixed frequencies Ar(+) laser lines, were recorded on a Connes-type Fourier transform interferometer. Molecular constants of the first 14 vibrational levels of the (2)(3)Sigma(+) state are determined. The RKR potential energy curve is derived. The main spectroscopic constants for this triplet electronic state of the (39)K (85)Rb isotopic species are T(e) = 13 507.146(2) cm(-1), omega(e) = 48.6385(6) cm(-1), B(e) = 0.0254152(5) cm(-1), gamma = 0.00164(4) cm(-1), epsilon = -0.469(2) cm(-1), R(e) = 4.98345 ?, 𝒟(e) = 3447 cm(-1). Copyright 2000 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.     

The Radial Hamiltonians for the X(1)Sigma(+) and B(1)Sigma(+) States of HCl

All literature vibration-rotational and pure rotational transition energies for the ground X(1)Sigma(+) electronic state of H(35)Cl, H(37)Cl, D(35)Cl, and D(37)Cl, along with the entire collection of electronic B(1)Sigma(+) --> X(1)Sigma(+) emission data for the four isotopomers, have been used in a least-squares fit of compact analytic Born-Oppenheimer potential functions for the B(1)Sigma(+) and X(1)Sigma(+) electronic states. Additional functions related to the adiabatic and nonadiabatic corrections have also been determined. Separate least-squares fits were made according to the hamiltonian operators of J. K. G. Watson (J. Mol. Spectrosc. 80, 411 (1980)) and R. M. Herman and J. F. Ogilvie (Adv. Chem. Phys. 103, 187 (1998)). The results from the separate analyses demonstrate clearly that the two hamiltonian operators are essentially equivalent, both achieving equally satisfactory representations of the spectral data, and furnishing virtually identical Born-Oppenheimer potential functions. Fully quantum-mechanical vibrational eigenvalues and rotational perturbation series parameters B(v)-O(v) are presented for the lower levels of the X(1)Sigma(+) ground state for which infrared and/or microwave data are available (v" 相似文献   

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 Laser Spectroscopy of YbCl: The A(2)Pi-X(2)Sigma(+) Transition

The A(2)Pi-X(2)Sigma(+) transition of (174)Yb(35)Cl and (172)Yb(35)Cl has been rotationally analyzed for the first time. Doppler-limited laser excitation spectroscopy with selective detection of fluorescence was used to obtain spectra of the 0-0 and 1-0 bands with a measurement accuracy of approximately 0.0035 cm(-1). Resolved fluorescence was used to record the 0-1, 0-2, and 0-3 bands and to unequivocally assign the rotational numbering, N, to the laser excitation spectra. In total, over 1300 line positions have been measured and assigned for each of the two isotopomers and employed in least-squares fits of molecular parameters. The principal results for the A(2)Pi state are A(e) = 1491.494(2) cm(-1) and R(e) = 2.4433(1) ?, and for the X(2)Sigma(+) state, R(e) = 2.4883(2) ? and gamma(e) = 4.59(2) x 10(-3) cm(-1). The interaction between the X(2)Sigma(+) and A(2)Pi states has been investigated and is shown to be the main contributor to the spin-rotation splitting in the ground state. Copyright 2000 Academic Press.     

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.     

High-Resolution Laser Spectroscopy of YbCl: The B(2)Sigma(+)-X(2)Sigma(+) Transition

High-resolution laser excitation spectra have been obtained for the 0-0, 1-1, and 0-1 bands of the B(2)Sigma(+)-X(2)Sigma(+) transition of YbCl and a rotational analysis has been performed on the (174)Yb(35)Cl and (172)Yb(35)Cl isotopomers. Comparison of the spin-rotation constant, gamma, for the B(2)Sigma(+) state with the lambda-doubling constant of the A(2)Pi(1/2) state (1) shows that the two excited states form a unique perturber pair arising from the 6psigma and 6ppi orbitals centered on the Yb(+) ion. The principal results for the B(2)Sigma(+) state are B(e)=0.097552(5) cm(-1), R(e)=2.43623(6) ?, gamma(e)=-2.1655(6)x10(-4) cm(-1), and DeltaG(1/2)=313.111(2) cm(-1). Copyright 2001 Academic Press.     

Near-Infrared Spectrum of the A(2)Pi(i)-X(2)Sigma(+) (2,0) Band of CN Studied by Concentration Modulation Laser Spectroscopy

The rotational structure of (2,0) vibrational band of A(2)Pi(i)-X(2)Sigma(+) transition of CN has been studied by concentration-modulation laser spectroscopy using a Ti:sapphire laser. The CN radical was produced in the ac glow discharge of acetonitrile with helium as the carrier gas. All 12 branches including four new branches have been observed and measured with an absolute accuracy of 0.007 cm(-1) in the region 12 450-12 750 cm(-1). Analysis of the spectra has led to improved molecular parameters of the A(2)Pi(i) (v' = 2) state. Copyright 2001 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.     

The Electronic Spectrum of Germanium Monosulfide: Rotational Structure in the A(1)Pi-X(1)Sigma(+) Transition in (70)GeS

The emission spectrum of the specific isotopomer (70)GeS was excited in a microwave (2450-MHz) discharge and the A(1)Pi-X(1)Sigma(+) transition (270-430 nm) was photographed under high resolution on a 10.6-m Ebert grating spectrograph. The rotational analysis of 43 bands led to the determination of accurate vibrational and rotational constants. Making use of these constants, the potential energy curves for the A(1)Pi and X(1)Sigma(+) states were generated by the RKR method and Franck-Condon factors and r-centroids were computed for the bands analyzed. The present extensive high-resolution study has revealed only a few localized perturbations in the A(1)Pi (v'=4, 5, 9) vibronic states, which contrasts with the situation in the isovalent molecules such as GeO, SiS, and SiSe. 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.     

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   

The Comet-Tail (A(2)Pi(i)-X(2)Sigma(+)) System of (12)C(16)O(+): A Reinvestigation

The emission spectrum of the comet-tail (A(2)Pi(i)-X(2)Sigma(+)) system of (12)C(16)O(+) produced in the cathode glow of a hollow-cathode discharge tube and photographed in the spectral region 3345-8500 ? at high resolution was reinvestigated. Detailed rotational analysis of 10 bands involving 5 vibrational levels v = 0 to 4 of each of the A and X states was carried out. Spin-splitting of the rotational levels was observed for the analyzed bands. The observed intensity distribution of the branches is found to be in good agreement with theoretical calculations. Molecular constants for both the A and X states were obtained from a global fit of the present data of the A-X system and the infrared and microwave data available from the literature for v = 0, 1, 2, 3, and 4 of state X, using effective Hamiltonian for the A(2)Pi state and matrix elements for both A and X states. The present work suggests that the A(2)Pi(i) state changes from Hund's case (a) at low J values to Hund's case (b) at high J values. 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.     

Experimental Characterization of the Higher Vibrationally Excited States of HCO(+): Determination of omega(2), x(22), g(22), and B(030)

Analyses of high Rydberg series of HCO converging to the (030) vibrational state of the cation establish rovibrational state-detailed thresholds for HCO(+). UV-visible laser double resonance isolates series for assignment. Strongly vertical Rydberg-Rydberg transitions from photoselected N' = 0 and N' = 2 rotational levels of the Sigma(-) Renner-Teller vibronic component of the 3ppi (2)Pi (030) complex define individual series converging to rotational levels, N(+) = 1 through 5 and 3 through 5 of the HCO(+) vibrational states (03(1)0) and (03(3)0), respectively. Extrapolation of autoionizing series locates the positions of these rovibrational states to within +/-0.01 cm(-1). The use of this information combined with precise ionization limits for lower vibrational states determined from earlier Rydberg extrapolations and spectroscopic information available from infrared absorption measurements enables an estimate of the force-field parameters for HCO(+) bending. These parameters include the harmonic bending frequency, omega(2) = 842.57 cm(-1), the vibrational angular momentum splitting constant, g(22) = 3.26 cm(-1), and the diagonal bending anharmonicity, x(22) = -2.53 cm(-1), separated from the off-diagonal contribution, x(12), by reference to ab initio calculations. Results of experiment on the higher vibrationally excited states of HCO(+) are compared with recent theoretical predictions. Copyright 2000 Academic Press.     

A Reinvestigation of the c(3)Pi-X(1)Sigma(+) (0-0) Absorption Band of Carbon Monoxide

The forbidden c(3)Pi-X(1)Sigma(+) (0-0) absorption band of carbon monoxide has been reinvestigated under different pressure conditions using the 10.7-m VUV spectrograph at Meudon. Overlap with the allowed C(1)Pi-X(1)Sigma(+) (0-0) band at lower transition energy has been taken into account. We have identified a new rotational branch corresponding to an S-type branch and extended the analysis to both higher and lower J. An analysis of the band structure and the low J transition lines suggests that the band gains its intensity predominantly as a result of an interaction of the c(3)Pi state with a (1)Sigma(+) state, most likely the C(1)Sigma(+) (v = 0) state. Molecular constants have been obtained for the c(3)Pi state that are in reasonable agreement with those previously published. The apparently anomalous small value for the centrifugal distortion constant is explained by a homogeneous perturbation with the k(3)Pi valence state. 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.     

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   

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.