Intense-field modulation of NO2 multiphoton dissociation dynamics

We report on the dynamics of multiphoton excitation and dissociation of NO(2) at wavelengths between 395 and 420 nm and intensities between 4 and 10 TW cm(-2). The breakup of the molecule is monitored by NO A (2)Sigma(+)n(')=1,0-->X (2)Pi(r)n(")=0 fluorescence as a function of time delay between the driving field and a probe field which depletes the emission. It is found that generation of n(')=0 and 1 NO A (2)Sigma(+) results in different fluorescence modulation patterns due to the intense probe field. The dissociation dynamics are interpreted in terms of nuclear motions over light-induced potentials formed by coupling of NO(2) valence and Rydberg states to the applied field. Based on this model, it is argued that the time and intensity dependences of A (2)Sigma(+)n(')=0-->X (2)Pi(r)n(")=0 fluorescence are consistent with delayed generation of NO A (2)Sigma(+)n(')=0 via a light-induced bond-hardening brought about by the transient coupling of the dressed A (2)B(2) and Rydberg 3ssigma (2)Sigma(g) (+) states of the parent molecule. The increasingly prompt decay of A (2)Sigma(+)n(')=1-->X (2)Pi(r)n(")=0 fluorescence with increasing intensity, on the other hand, is consistent with a direct surface crossing between the X (2)A(1) and 3ssigma (2)Sigma(g) (+) dressed states to generate vibrationally excited products.     

A theoretical study of the fine and hyperfine interactions in the NCO and CNO radicals

The geometries, the harmonic vibrational frequencies, and the Renner-Teller parameter have been reported for the NCO(+)(X (3)Sigma(-)), NCO(X (2)Pi,A (2)Sigma(+),B (2)Pi,2 (2)Sigma(+)), NCO(-)(X (1)Sigma(+)), CNO(+)(X), CNO(X (2)Pi,A (2)Sigma(+),B (2)Pi,2 (2)Sigma(+)), and CNO(-)(X (1)Sigma(+)) systems at the full valence-complete active space self-consistent-field (fv-CASSCF) level of theory. The (2)Pi electronic states of the NCO and CNO radicals have two distinct real vibrational frequencies for the bending modes and these states are subject to the type A Renner-Teller effect. The total energy of CNO(+) without zero point energy correction of the linear geometry is approximately 31 cm(-1) higher than the bent geometry at the fv-CASSCF level and the inversion barrier vanishes after the zero point energy correction; therefore, the ground state of the CNO(+) may possess a quasilinear geometry. The spin-orbit coupling constants estimated using atomic mean field Hamiltonian at the fv-CASSCF level of theory are in better agreement with the experimental values. The excitation energies, the electron affinity, and the ionization potential have been computed at the complete active space second order perturbation theory (CASPT2) and the multireference singles and doubles configuration (MRSD-CI) levels of theory. The computed values of the electric hyperfine coupling constants for the (14)N atom in the ground state of the NCO radical agree well with the experimental data. The magnetic hyperfine coupling constants (HFCC's) have been estimated employing the configuration selected MRSD-CI and the multireference singles configuration interaction (MRS-CI) methods using iterative natural orbitals (ino) as one particle basis. Sufficiently accurate value of the isotropic contribution to the HFCC's can be obtained using an MRS-CI-ino procedure.     

Ab initio investigation of potential energy curves of the 23 electronic states of IBr correlating to neutral (2)P atoms

Potential energy surfaces for all Born-Oppenheimer electronic states of IBr molecule correlating to the neutral (2)P ((2)P(3/2) and (2)P(1/2)) iodine and bromine are calculated for the first time. Electric dipole and polarizability curves (static and transition) are also determined. Calculations include scalar and spin-orbit relativistic effects within all-electron Douglas-Kroll two-component Hamiltonian. Electron correlation is treated with quasi-degenerate multi-reference second-order perturbation theory. Seven adiabatic electronic states (X (1)Sigma(+), A'(3)Pi(2), A (3)Pi(1), 1 (3)Pi(0-), B (3)Pi(0+), B'(3)Sigma, and 2 (3)Pi(0+)) exhibit significant covalent bonding, and can support vibrational states. Calculated spectroscopic parameters agree with experiment to better than 1000 cm(-1) (T(e)), 10 cm(-1) (omega(e)), and 0.05 Angstrom (r(e)). A new 1 (3)Pi(0-) state correlating to ground-state atoms is predicted at T(e) approximately 14 000 cm(-1), omega(e) approximately 80 cm(-1), and r(e) approximately 3.0 Angstrom. The second new state (2 (3)Pi(0+)) correlates to excited iodine atom, with T(e) approximately 20 000 cm(-1), omega(e) approximately 115 cm(-1), and r(e) approximately 3.3 Angstrom. Non-adiabatic coupling parameters are calculated for the four avoided crossings, which arise due to electronic spin-orbit interaction. Estimated parameters of the B (3)Pi(0+)/B'(3)Sigma crossing (R(c) approximately 3.32 Angstrom; V approximately 120 cm(-1)) agree with experimental values. The previously unsuspected 2 (3)Pi(0-)/1 (1)Sigma(-) crossing of two repulsive surfaces provides a new collisional deactivation channel for Br* atoms at relative velocities above 1000 m s(-1). Several repulsive states (including 1 (1)Pi(1) and 2 (3)Pi(1)) intersect the B/B' system near the avoided crossing point, and may affect dynamics of IBr in strong laser fields.     

Observation of L uncoupling in the 5 1Deltag Rydberg state of Na2

The phenomenon of electronic orbital angular momentum L uncoupled from its internuclear axis has been observed in the sodium dimer using high-resolution cw optical-optical double-resonance spectroscopy. When L uncoupling occurs, the degeneracy of Lambda doubling is removed. In our experiment, the intermediate B (1)Pi(u) state of Na(2) is excited from the thermally populated ground X (1)Sigma(g) (+) state by a single-line Ar(+) laser. Then, a single-mode dye laser is used to probe the Rydberg states from the intermediate state. The signals are detected by monitoring the UV fluorescence from the triplet gerade states back to the a (3)Sigma(u) (+) state via collision energy transfer. Under our experimental resolution, the splitting of Lambda doubling in the 5 (1)Delta(g) state of Na(2) can be measured. A total of 136 rovibronic levels with ef parities have been assigned to the 5 (1)Delta(g) state. The Lambda-splitting constants deduced from these data are q(0)=0.376(90)x10(-4) cm(-1), q(v)=0.114(6)x10(-4) cm(-1), and mu=0.76(33)x10(-8) cm(-1). In general, the Lambda splitting of the Delta states is considerably smaller than that of the Pi states. However, the first-order splitting constants q(0) and q(v) reported here are larger than those in the B (1)Pi(u) state. This is due to the L uncoupling of the Rydberg states.     

Laser induced amplified spontaneous emission from the B2Pi, L2Pi, and I2Sigma+ valence states of NO

Amplified spontaneous emission (ASE) from single rovibrational levels of valence (non-Rydberg) states of NO molecules has been investigated. The B2Pi (v=24 and 25), L2Pi (v=5 and 6), and I2Sigma+ (v=6) levels have been populated through laser optical-optical double resonance excitation via the Rydberg A2Sigma+ state. Term values for the 2Pi states have been determined with an accuracy of +/-0.03 cm(-1). Analyses of rotationally resolved dispersed ASE spectra in the near infrared region have shown that all the lower states belonged to the Rydberg states. The valence approximately Rydberg coupling in the upper manifolds has driven ASE systems from the valence to the Rydberg levels where they benefit from the strong intensities of inter-Rydberg transitions with Deltav=0. The experimentally predicted valence approximately Rydberg interactions have been compared with theoretical treatments.     

Electronic states and spectroscopic properties of SiTe and SiTe+

Ab initio based configuration interaction calculations have been carried out to study the low-lying electronic states and spectroscopic properties of the heaviest nonradioactive silicon chalcogenide molecule and its monopositive ion. Spectroscopic constants and potential energy curves of states of both SiTe and SiTe+ within 5 eV are reported. The calculated dissociation energies of SiTe and SiTe+ are 4.41 and 3.52 eV, respectively. Effects of the spin-orbit coupling on the electronic spectrum of both the species are studied in detail. The spin-orbit splitting between the two components of the ground state of SiTe+ is estimated to be 1880 cm(-1). Transitions such as 0+ (II)-X1Sigma(+)0+, 0+ (III)-X1Sigma(+)0+, E1Sigma(+)0+ -X1Sigma(+)0+, and A1Pi1-X1Sigma(+)0+ are predicted to be strong in SiTe. The radiative lifetime of the A1Pi state is less than a microsecond. The X(2)2Pi(1/2)-X(1)2Pi(3/2) transition in SiTe+ is allowed due to spin-orbit mixing. However, it is weak in intensity with a partial lifetime for the X2 state of about 108 ms. The electric dipole moments of both SiTe and SiTe+ in their low-lying states are calculated. The vertical ionization energies for the ionization of the ground-state SiTe to different ionic states are also reported.     

Absorption cross sections and correlation functions of the NH2 A 2A1-X2B1 Renner-Teller system

We present a quantum-mechanical study of absorption cross sections and correlation functions of the title system, using a spinless Hamiltonian that includes the nonadiabatic Renner-Teller (RT) coupling between the electronic states, and taking into account the nuclear-spin statistics. We consider also the stimulated emission, assuming a Boltzmann distribution of the molecular levels, and we express correlation functions in terms of wave-packet (WP) overlaps. Assuming that the body-fixed z component of the angular momentum is a constant of motion of isolated NH(2), we calculate X rotational and rovibrational, and X+A rovibronic cross sections and correlation functions at 4.2 and 300 K, up to 26 000 cm(-1) and 3000 fs. We also report the rotational spectrum at 3000 K. The number of absorbing states is large at high T, and the number of lines with appreciably intensity thus increases remarkably with T, from 67 at 4.2 K, to 847 at 300 K, and up to 10 609 at 3000 K. The cold spectrum consists only of Pi lines, due to ground-level absorption. At room and higher T, the hot spectrum presents long progressions of rovibronic lines. The strongest spectral intensities are X Pi and Phi rotational lines and A bending Sigma and Pi lines. We also find many Fermi resonances between A bending and combination states, and that approximately 50% of the lines belong to both electronic states. This latter result points out many RT couplings above 11 000 cm(-1). The theoretical intensities agree very well with the few available experimental data. The time evolution of the correlation functions reflects all internal motions, with periods ranging from approximately 750 to 2 fs, from slow rotational modes to ultrafast electronic dynamics. At low T, the correlation function is proportional to the survival probability of an initial WP, it has many recursions, and can be very regular, without decaying on the average. At high T, the correlation function is associated with the dynamics of many WPs, which present different dephasing times, and the dynamics thus becomes very irregular. The internal dynamics is nonadiabatic above 11 000 cm(-1), because the WPs move from the vertical to the linear region of the excited surface, and can jump to the ground surface owing to RT couplings.     

A theoretical study of the excited states of CrH: potential energies, transition moments, and lifetimes

Ab initio calculations of low-lying electronic states of CrH are presented, including potential energies, dipole and transition dipole moment (TDM) functions, and radiative lifetimes for X (6)Sigma(+), A (6)Sigma(+), 3 (6)Sigma(+), 1 (6)Pi, 2 (6)Pi, 3 (6)Pi, and (6)Delta. Calculation of dynamic correlation effects was performed using the multistate complete active space second-order perturbation method, based on state-averaged complete active space self-consistent-field reference wave functions obtained with seven active electrons in an active space of 16 molecular orbitals. A relativistic atomic natural orbital-type basis set from the MOLCAS library was used for Cr. Good agreement is found between the current calculations and experiment for the lowest two (6)Sigma(+) states, the only states for which spectroscopic data are available. Potential curves for the 3 (6)Sigma(+) and 2 (6)Pi states are complicated by avoided crossings with higher states of the same symmetry, thus resulting in double-well structures for these two states. The measured bandhead T(0)=27 181 cm(-1), previously assigned to a (6)Pi<--X (6)Sigma(+) transition, is close to our value of T(0)=28 434 cm(-1) for the 2 (6)Pi state. We tentatively assign the ultraviolet band found experimentally at 30 386 cm(-1) to the 3 (6)Pi<--X (6)Sigma(+) transition for which the computed value is 29 660 cm(-1). The A (6)Sigma(+)<--X (6)Sigma(+) TDM and A (6)Sigma(+) lifetimes are found to be in reasonable agreement with previous calculations.     

High resolution vacuum ultraviolet emission spectrum of D(2) from 78 to 103 nm: The D (1)Pi(u)-->X (1)Sigma(g) (+) and D(') (1)Pi(u) (-)-->X (1)Sigma(g) (+) band systems

The emission spectrum of the D(2) molecule has been studied at high resolution in the vacuum ultraviolet region 78.5-102.7 nm. A detailed analysis of the two D (1)Pi(u)-->X (1)Sigma(g) (+) and D(') (1)Pi(u) (-)-->X (1)Sigma(g) (+) electronic band systems is reported. New and improved values of the level energies of the two upper states have been derived with the help of the program IDEN [V. I. Azarov, Phys. Scr. 44, 528 (1991); 48, 656 (1993)], originally developed for atomic spectral analysis. A detailed comparison is made between the observed energy levels and solutions of coupled equations using the newest ab initio potentials by Wolniewicz and co-workers [J. Chem. Phys. 103, 1792 (1995); 99, 1851 (1993); J. Mol. Spectros. 212, 208 (2002); 220, 45 (2003)] taking into account the nonadiabatic coupling terms for the D (1)Pi(u) state with the lowest electronic states B (1)Sigma(u) (+), C (1)Pi(u), and B(') (1)Sigma(u) (+). A satisfactory agreement has been found for most of the level energies belonging to the D and D(') states. The remaining differences between observation and theory are probably due to nonadiabatic couplings with other higher electronic states which were neglected in the calculations.     

Parallel and coupled perpendicular transitions of RbCs 640 nm system: mass-resolved resonance enhanced two-photon ionization in a cold molecular beam

We have investigated the RbCs 640 nm system by mass-resolved resonance enhanced two-photon ionization in a cold molecular beam. Very complex vibronic structures were observed between 15420 and 15990 cm (-1). The parallel transitions of 2 (3)Pi 0 v' = 4-20 <-- X (1)Sigma (+) v' = 0 were identified by rotationally resolved spectra. Molecular constants and a Rydberg-Klein-Rees potential energy curve of the 2 (3)Pi 0 state were determined. The regular vibrational spacing of the parallel transition indicated that the 2 (3)Pi 0 state is not significantly perturbed by nearby excited electronic states. The complexity of the observed vibronic structures has been attributed to the coupled perpendicular transitions of 2 (1)Pi, 2 (3)Pi 1, and 3 (3)Sigma 1 (+) <-- X (1)Sigma (+) v' = 0. For the perpendicular bands observed in the lower-energy spectral region between 15420 and 15630 cm (-1) where the onsets of the 2 (3)Pi 1 and 3 (3)Sigma 1 (+) <-- X (1)Sigma (+) transitions are located, the upper electronic states and the vibrational quantum numbers were assigned. Perturbations of 2 (3)Pi 1-3 (3)Sigma 1 (+) and 2 (1)Pi-3 (3)Sigma 1 (+) have been identified by the observed level shifts.     

Laser spectroscopic studies of several Rydberg states of MgO

We report extensive spectroscopic measurements of rovibronic transitions from the MgO X 1Sigma+ ground state to the high-energy E 1Sigma+, F 1Pi1, and G 1Pi1 Rydberg states. Perturbations in the E 1Sigma+ and G 1Pi1 states were observed. The Rydberg molecular orbital character of the three states is examined, given ab initio calculations by Thummel et al. [Chem. Phys. 129, 417 (1989)]. It is concluded that the E 1Sigma+ and G 1Pi1 states consist primarily of the MgO+ X 2Pi ionic core, surrounded by 3ppi and 3psigma Rydberg electron clouds, respectively, and that the F 1Pi1 state consists primarily of the MgO+ A 2Sigma+ ionic core surrounded by a 3ppi Rydberg electron cloud. Spectroscopic characterizations of some unassigned vibrational levels of analogous MgO 3Pi2 states in this energy region are also reported.     

The 39K(2) 2(3)Sigma(g)+ state: observation and analysis

The (39)K(2) 2 (3)Sigma(g) (+) state has been observed by perturbation-facilitated infrared-infrared double resonance spectroscopy and two-photon excitation. Resolved fluorescence spectra into the a (3)Sigma(u) (+) state have been recorded. The observed vibrational levels have been assigned as the v=23-25, 27, 28, 31-33, 38-45, 47, and 53 levels by comparing the observed and calculated spectra of the 2 (3)Sigma(g) (+)-->a (3)Sigma(u) (+) transitions. Molecular constants have been obtained using a global fitting procedure with a comprehensive set of experimental data. Fine and hyperfine splittings have been resolved in the excitation spectra. Perturbations between the 2 (3)Sigma(g) (+) and 2 (3)Pi(g) states were observed. The hyperfine patterns of the 2 (3)Sigma(g) (+) levels are strongly affected by the perturbation. The perturbation-free and weakly perturbed levels follow the case b(betaS) coupling scheme, while the perturbed levels follow case b(beta J) coupling. A Fermi contact constant, b(F)=65+/-10 MHz, has been obtained. Intensity anomalies of rotational lines appeared both in the 2 (3)Sigma(g) (+) approximately 2 (3)Pi(g)<--b (3)Pi(u) excitation spectra and in the 2 (3)Sigma(g) (+) approximately 2 (3)Pi(g)-->a (3)Sigma(u) (+) resolved fluorescence spectra. These intensity anomalies can be explained in terms of a quantum-mechanical interference effect.     

A theoretical study of calcium monohydride, CaH: low-lying states and their permanent electric dipole moments

Potential energy curves, energy parameters, and spectroscopic values for the X (2)Sigma(+), A (2)Pi, B (2)Sigma(+), a (4)Pi, and b (4)Sigma(+), states of CaH have been calculated using the multireference configuration interaction and coupled cluster levels of theory, while employing quantitative basis sets (of augmented quintuple-zeta quality) and taking also into account core/valence correlation and one-electron relativistic effects. For the ground (X (2)Sigma(+)) and the first two following excited states (A (2)Pi, B (2)Sigma(+)) of CaH, the permanent electric dipole moments have been calculated. Our best finite field dipole moment of the A (2)Pi state of 2.425 D (upsilon = 0) is in very good agreement with the experimental literature value of 2.372(12) D. However, a discrepancy is observed in the dipole moment of the X (2)Sigma(+) state. Our most extensive calculation gives mu = 2.623 D (upsilon = 0), which is considerably smaller than the experimental value of mu = 2.94(16) D (upsilon = 0). Small van der Waals minima were found for both "repulsive" quartet states. Spectroscopic constants and energy parameters for all states are in remarkable agreement with available experimental values.     

Ab initio study of the low lying electronic states of ZnF and ZnF-

Highly correlated ab initio calculations have been performed for an accurate determination of the electronic structure and of the spectroscopy of the low lying electronic states of the ZnF system. Using effective core pseudopotentials and aug-cc-pVQZ basis sets for both atoms, the potential curves, the dipole moment functions, and the transition dipole moments between relevant electronic states have been calculated at the multireference-configuration-interaction level. The spectroscopic constants calculated for the X(2)Sigma(+) ground state are in good agreement with the most recent theoretical and experimental values. It is shown that, besides the X(2)Sigma(+) ground state, the B(2)Sigma(+), the C(2)Pi, and the D(2)Sigma(+) states are bound. The A(2)Pi state, which has been mentioned in previous works, is not bound but its potential presents a shoulder in the Franck-Condon region of the X(2)Sigma(+) ground state. All of the low lying quartet states are found to be repulsive. The absorption transitions from the v=0 level of the X(2)Sigma(+) ground state toward the three bound states have been evaluated and the spectra are presented. The potential energy of the ZnF(-) molecular anion has been determined in the vicinity of its equilibrium geometry and the electronic affinity of ZnF (EA=1.843 eV with the zero energy point correction) has been calculated in agreement with the photoelectron spectroscopy experiments.     

Ground state potential energy curve and dissociation energy of MgH

New high-resolution visible emission spectra of the MgH molecule have been recorded with high signal-to-noise ratios using a Fourier transform spectrometer. Many bands of the A 2Pi-->X 2Sigma+ and B' 2Sigma+-->X 2Sigma+ electronic transitions of 24MgH were analyzed; the new data span the v' = 0-3 levels of the A 2Pi and B'2Sigma+ excited states and the v'=0-11 levels of the X 2Sigma+ ground electronic state. The vibration-rotation energy levels of the perturbed A 2Pi and B' 2Sigma+ states were fitted as individual term values, while those of the X 2Sigma+ ground state were fitted using the direct-potential-fit approach. A new analytic potential energy function that imposes the theoretically correct attractive potential at long-range, and a radial Hamiltonian that includes the spin-rotation interaction were employed, and a significantly improved value for the ground state dissociation energy of MgH was obtained. The v'=11 level of the X 2Sigma+ ground electronic state was found to be the highest bound vibrational level of 24MgH, lying only about 13 cm(-1) below the dissociation asymptote. The equilibrium dissociation energy for the X 2Sigma+ ground state of 24MgH has been determined to be De=11104.7+/-0.5 cm(-1) (1.37681+/-0.00006 eV), whereas the zero-point energy (v'=0) is 739.11+/-0.01 cm(-1). The zero-point dissociation energy is therefore D0=10365.6+/-0.5 cm(-1) (1.28517+/-0.00006 eV). The uncertainty in the new experimental dissociation energy of MgH is more than 2 orders of magnitude smaller than that for the best value available in the literature. MgH is now the only hydride molecule other than H2 itself for which all bound vibrational levels of the ground electronic state are observed experimentally and for which the dissociation energy is determined with subwavenumber accuracy.     

The permanent electric dipole moments of WN and ReN and nuclear quadrupole interaction in ReN

The high-resolution laser induced fluorescence spectra of tungsten mononitride WN and rhenium mononitride ReN have been recorded in a laser ablation/molecular beam spectrometer. The field free spectrum of the (0,0)A (4)Pi(3/2)-X (4)Sigma(1/2) (-) band system of (186)WN has been analyzed to produce B("), B('), and gamma(") values of 0.4659(2), 0.4554(2), and 0.0518(1) cm(-1), respectively. The permanent electric dipole moments mu for the X (4)Sigma(1/2) (-) and A (4)Pi(3/2) state were determined to be 3.77(18) and 2.45(3) D, respectively, from the analysis of the optical Stark effect. The (0,0)[26.0]0(+)-X0(+) band system of ReN was recorded in the presence of a variable static electric field. The ground and excited state electric dipole moments of (187)ReN were determined to be mu(X0(+))=1.96(8) D and mu([26.0]0(+))=3.53(4) D. Splittings in the field free (187)ReN spectrum were analyzed to produce (187)Re (I=5/2) nuclear electric quadrupole coupling constants e(2)Qq(0) of -0.0304(8) and 0.0328(9) cm(-1) for the X0(+) and [26.0]0(+) states, respectively. A molecular orbital correlation model is used to interpret the observation and a comparison is made to CrN and MoN.     

Study on the photodissociation spectra of CS2+ via B2Sigma u+ and C2Sigma g+ electronic states

The photodissociation spectra of CS(2)(+) ions via B(2)Sigma(u)(+) and C(2)Sigma(g)(+) electronic states have been studied by using two-photon excitation, where the parent CS(2)(+) ions were prepared by [3 + 1] REMPI (resonance-enhanced multiphoton ionization) at 483.2 nm from the jet-cooled CS(2) molecules. The [1 + 1] photodissociation spectrum of CS(2)(+) via the B(2)Sigma(u)(+)(upsilon(1)upsilon(2)0) <-- X(2)Pi(g,3/2)(000) transition was obtained by scanning the dissociation laser in the wavelength range of 270-285 nm and detecting the signal of both S(+) and CS(+). The [1 + 1'] photodissociation spectra of CS(2)(+) were obtained by fixing the first dissociation laser at 281.94 or 277.15 nm to excite the B(2)Sigma(u)(+) (000 or 100) <-- X(2)Pi(g,3/2)(000) transitions and scanning the second dissociation laser in the range of 606-763 nm to excite C(2)Sigma(g)(+)(upsilon(1)upsilon(2)0) <-- B(2)Sigma(u)(+)(000,100) transitions. New spectroscopic constants of nu(1) = 666.2 +/- 2.5 cm(-1), nu(2) = 363.2 +/- 1.9 cm(-1), chi(11) = -5.5 +/- 0.1 cm(-1), chi(22) = 1.6 +/- 0.1 cm(-1), chi(12) = -8.6 +/- 0.2 cm(-1), and k(122) = 44.9 +/- 2.5 cm(-1) (Fermi resonance constant) for the C(2)Sigma(g)(+) state are deduced from the [1 + 1'] photodissociation spectra. On the basis of the [1 + 1] and [1 + 1'] photodissociation spectra, the wavelength and level dependence of the product branching ratios CS(+)/S(+) has been found and the dissociation dynamics of CS(2)(+) ions via B(2)Sigma(u)(+) and C(2)Sigma(g)(+) electronic states are discussed.     

Doubly excited 2 1Delta g state of Na2

The doubly excited valence (3p+3p) 2 (1)Delta(g) state of Na(2) is experimentally observed by using optical-optical double resonance spectroscopy. A single line Ar(+) laser (a total of nine lines) was used to pump the sodium dimers from thermally populated ground state X (1)Sigma(g) (+) to the intermediate B (1)Pi(u) state. Then, a single mode Ti:sapphire laser was used to probe the doubly excited 2 (1)Delta(g) state. Violet fluorescence emitted from the highly excited states (mainly 2 (3)Pi(g) or 3 (3)Pi(g) states which are transferred from 2 (1)Delta(g) state via collision) to the a (3)Sigma(u) (+) state was monitored by a filtered photomultiplier tube (PMT). A total of 582 rovibrational levels of 2 (1)Delta(g) state were observed, identified, and assigned to the vibrational and rotational quantum numbers in the range of 0< or =v< or =28 and 11< or =J< or =99, respectively. The absolute vibrational quantum number assignment was verified by comparing the totally resolved fluorescence with the calculated Franck-Condon factors between 2 (1)Delta(g) state and B (1)Pi(u) state. Dunham coefficients and Rydberg-Klein-Rees potential curve were derived from these observed quantum levels. The primary molecular constants of Na(2) 2 (1)Delta(g) state are T(e)=32 416.759(15) cm(-1), omega(e)=124.8484(36) cm(-1), B(e)=0.119 158(3) cm(-1), and R(e)=3.508 20(5) A.     

The spin-orbit and rotational constants for the N2 C" 5Pi(ui) (v = 3) state

The spin-orbit (A = -16.4 cm(-1)) and rotational (B = 1.017 cm(-1)) constants for the N2 C" 5Pi(ui)(v = 3) level are determined by a fit to rotational lines in the C" 5Pi(u)-A' 5Sigma(g)+(3-1) band that terminate in J'Omega' = 3(3), 4(3), 3(2), and 4(2) levels of the C" state. The C"-state spin-orbit constant is consistent with semi-empirical estimates, based on spin-orbit constants observed in several other electronic states of N2 and the atomic spin-orbit coupling constant, zeta(N 2p). The C"-A' bands exhibit the unusual feature of oppositely degraded sub-band heads, Omega' = 3 (red) and Omega' = 1, 0, and -1 (blue). The unusually wide range of B(Omega)eff values, from 0.85 cm(-1) (Omega = 3) to 1.28 cm(-1) (Omega = -1) for C" 5Pi(v = 3) should be diagnostically useful for Omega'-assignments. The C" 5Pi(v = 3) level lies 14257.17 and 90599 cm(-1) above A' 5Sigma(g)+(v = 1) and X 1Sigma(g)+(v = 0), respectively, and Re(C" 5Pi) = 1.50 A.