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.     

Further Investigations of the ClO Rotational Spectrum

Pure rotational transitions of the chlorine monoxide radical have been observed up to v=2 in the X(1) (2)Pi(3/2) and X(2) (2)Pi(1/2) states and transitions of the (35)Cl(18)O isotopomer have been observed in natural abundance. Additionally, rotational transitions for levels up to J'=115/2 have been measured in the far infrared. These data have been merged with the existing microwave, submillimeter, and high-resolution infrared transition frequencies and fit simultaneously with a set of isotopically independent parameters. Isotopic substitution of both the Cl and O atoms has enabled the first determination of the electron spin-rotation constant gamma=-296.0(43) MHz as well as the Born-Oppenheimer corrections to the rotational constants. 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.     

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 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 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.     

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   

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.     

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.     

Far-infrared LMR spectroscopy of NF a1Δ (v = 0, 1, 2)

Far-infrared LMR spectra of NF in its a¹Δ state have been detected and assigned. Lines in two rotational transitions of both v = 0 and v = 1 states were measured for analysis. The derived constants are in excellent agreement with earlier EPR work (hyperfine parameters, v = 0) and with diode laser spectroscopy (rotational constants for v = 0 and 1). Using the optimized parameters it is shown that there is a significant decrease in the fluorine hyperfine constant on vibrational excitation. One rotational transition from $\text{v = 2}\text{NF}{}^1\text{Δ}$ has also been assigned.     

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.     

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.     

The nu(1) and nu(3) Bands of the (17)O(16)O(17)O Isotopomer of Ozone

Using 0.002 cm(-1) resolution Fourier transform absorption spectra of an (17)O-enriched ozone sample, an extensive analysis of the nu(3) band together with a partial identification of the nu(1) band of the (17)O(16)O(17)O isotopomer of ozone has been performed for the first time. As for other C(2v)-type ozone isotopomers [J.-M. Flaud and R. Bacis, Spectrochim. Acta, Part A 54, 3-16 (1998)], the (001) rotational levels are involved in a Coriolis-type resonance with the levels of the (100) vibrational state. The experimental rotational levels of the (001) and (100) vibrational states have been satisfactorily reproduced using a Hamiltonian matrix which takes into account the observed rovibrational resonances. In this way precise vibrational energies and rotational and coupling constants were deduced and the following band centers nu(0)(nu(3)) = 1030.0946 cm(-1) and nu(0)(nu(1)) = 1086.7490 cm(-1) were obtained for the nu(3) and nu(1) bands, respectively. Copyright 2000 Academic Press.     

Fourier Transform Spectra of the E(2)Pi(u)-X(2)Pi(g)((3/2)) System of CuCl(2)

High-resolution Fourier transform spectra of the laser-induced fluorescence of (63)Cu(37)Cl(2) produced in a cell have been recorded following excitation of a single vibronic level of the E(2)Pi(u) electronic state. Fluorescence occurs in combination bands to a broad spread of levels in the ground electronic state. A global vibronic model is proposed for the ground state based on an effective Hamiltonian, which fits the experimental data (2782 fluorescence lines, lower state quantum numbers: v(1) = 0-6, v(2) = 0-2, v(3) = 0-6, and J = 4(1/2)-80(1/2)) to 0.019 cm(-1) rms error. Vibrational, rotational and Renner-Teller parameters are obtained (e.g., omega(2) = 95.195(36) cm(-1), B(e) = 0.055106(3) cm(-1), epsilon = -0.1893(28)). A revised value for the equilibrium internuclear distance Cu-Cl is deduced: r(e)(Cu-Cl) = 0.20341(3) nm. The energy diagram of vibronic levels in the ground state is plotted up to 4000 cm(-1). Copyright 2000 Academic Press.     

CF X^2П（ν=1）远红外及NO X^2П（ν←0）中红外激光磁共振光谱的标识

根据塞曼效应理论和浙江磁共振（LMR）光谱原理,本文建立一了套用于标识激光磁共振光谱的模型方法,并成功地对CF X^2П（ν=1）远红外及NO X^2П（ν←0）中红外激光磁共振光谱进行了标识。为新自由基分子的激光磁共振光谱提供了快速而准确的方法。     

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.     

Rotational spectrum of ONCl in the (0, 0, 1) and (0, 1, 0) vibrational states and “b” type spectrum in the ground state. Comparison of force field obtained by different combinations of experimental data

From the rotational spectrum of ONCl in (0, 0, 1) and (0, 1, 0) excited vibrational states the inertia defects in these states have been determined. The “b” type rotational spectrum in the ground state has also been measured allowing the determination of Δ⁰ and of all the first-order centrifugal distortion constants.It is shown that by using differences of inertia defects Δ₂ and Δ₃ together with centrifugal distortion constants which do not involve the planarity relations and with harmonic vibrational frequencies of two isotopic species, the harmonic vibrational frequencies of two other isotopic species can be satisfactorily predicted.By using only inertia defects differences Δ₂ and Δ₃ as extra data, a definite choice can be made among the three sets of force constants which equally well reproduce the harmonic frequencies of four isotopic species.     

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   

High-Resolution Spectroscopy of Jet-Cooled (32)SO(2) and (34)SO(2): The ã(3)B(1)-;X(1)A(1), 2(1)(0) and 1(1)(0) Bands

Laser-induced excitation spectra of the two bands ?(3)B(1)-;X(1)A(1), 2(1)(0) and 1(1)(0) of (32)SO(2) and (34)SO(2) have been recorded in a supersonic jet at a resolution of 0.015 cm(-1). The rotational and electron-spin fine structure has been analyzed for both isotopic species. Analysis of the rotational and electron-spin fine structure yields precise values of the rotational constants A, B, and C and the spin constants alpha and beta for both (32)SO(2) and (34)SO(2) in the states ?(3)B(1) (010) and (100). No interaction between these two vibrational states with any nearby triplet state is observed for rotational levels with J 相似文献