Spectroscopic characterization of the Zn(4s(2))center dot Ne[(1)Sigma(+)] and Zn(4s4p pi)center dot Ne[(1)Pi(1)] van der Waals states

The Zn(4s2)·Ne[1Σ+] and the Zn(4s4pπ)·Ne[1Π1] states have been characterized by laser-induced fluorescence spectroscopy. Bond lengths were determined from simulations of the partially-resolved rotational structure of the 1Π ← 1Σ+ transitions, while bond strengths were estimated from a Birge–Sponer extrapolation with allowance for consistent errors resulting from similar procedures in the analogous Cd·Ne and Hg·Ne transitions. The van der Waals bonding in these states is discussed briefly and compared to that in the analogous M·RG states, where M=Mg, Zn, Cd, Hg and RG=Ne, Ar, Kr, Xe

Spectroscopic characterization of the Zn(4s(2))center dot Ne[(1)Sigma(+)] and Zn(4s4p pi)center dot Ne[(1)Pi(1)] van der Waals states

The Zn(4s2)·Ne[1Σ+] and the Zn(4s4pπ)·Ne[1Π1] states have been characterized by laser-induced fluorescence spectroscopy. Bond lengths were determined from simulations of the partially-resolved rotational structure of the 1Π ← 1Σ+ transitions, while bond strengths were estimated from a Birge–Sponer extrapolation with allowance for consistent errors resulting from similar procedures in the analogous Cd·Ne and Hg·Ne transitions. The van der Waals bonding in these states is discussed briefly and compared to that in the analogous M·RG states, where M=Mg, Zn, Cd, Hg and RG=Ne, Ar, Kr, Xe

Laser Spectroscopic Studies of the E 1£+ State of the MgO Molecule

The E1Σ+ ‘Rydberg' state of 24Mg16O has been characterized by two-color resonance-enhanced two-photon ionization (R2PI) spectroscopy in the 36 000–40 000 cm−1 region. Several rotationally resolved bands, assigned consistently to 24Mg16O(E1Σ+←X1Σ+) vibronic transitions, have been analyzed. The effective Bv′(v′=0−8) constants determined exhibit an unusual variation with v′. Possible causes of this variation are discussed. Estimated spectroscopic constants for the E1Σ+ state are reported

A pair potentials study of matrix-isolated atomic zinc. II. Intersystem crossing in rare-gas clusters and matrices

The mechanism of 4p 1P1→4p 3PJ intersystem crossing (ISC) following excitation of the 4p 1P1 level of matrix-isolated atomic zinc is investigated using a pair potentials approach. This is achieved by extending earlier ISC calculations on the Zn⋅RG2 and Zn⋅RG3 complexes to the square planar Zn⋅RG4 and square pyramidal Zn⋅RG5 species which are the building blocks of the Zn⋅RG18 cluster used to represent the isolation of atomic zinc in the substitutional site of a solid rare-gas host. ISC predictions in these clusters are based on whether crossing of the strongly bound 1A1 states, having a 4p 1P1 atomic asymptote, occurs with the repulsive 3E states correlating with the 4p 3PJ atomic level of atomic zinc. Predictions based on 1A1/3E curve crossings for 3E states generated with the calculated ab initio points for the Zn⋅RG 3Σ(pz) states do not agree with matrix observations. Based on similar overestimation of ISC in the Zn⋅RG diatomics, less repulsive Zn⋅RG 3Σ(pz) potential curves are used resulting in excellent agreement between theory and observations in the Zn–RG matrix systems. 1A1/3E curve crossings do not occur in the Zn–Ar system which shows only singlet emission. Curve crossings are found for the Zn–Xe system which exhibits only triplet emission. The Zn–Kr system does not show a crossing of the body mode Q2, which exhibits a strong singlet emission at 258 nm while the waist mode Q3, does have a crossing, resulting in a weak singlet emission at 239 nm and a stronger triplet emission at 312 nm. The efficiency of ISC is determined from Landau–Zener estimates of the surface hopping probabilities between the 1A1 and the 3E states. Differences in the application of this theory in the gas and solid phase are highlighted, indicating that the rapid dissipation of the excited-state energy which occurs in the solid must be included to obtain agreement with observations

Reactions in van der waals complexes, on experimental approach to the reactive surfaces of Hg (

A new technique is described for probing the reaction dynamics of “half-collisions” in systems where “full-collision” chemical dynamics can also be studied. By selective laser excitation of an atom-molecule van der Waal’s complex, an electronically excited atom can be created at a known distance from, and with a known orbital symmetry with respect to, the reactive molecule. From spectra of the complex and from detection of nascent products in a state-resolved fashion, not only can a great deal be learned about the dynamics of the “half-collision”, but comparison can also be made with analogous full-collision dynamical information. Reported here are results involving the Hg-H2 (63P1) van der Waal’s complex, where the two different orientations of the Hg 6p orbital is shown spectroscopically to exhibit widely different reactivities

Spectroscopic characterization of the unusually strongly bound, doubly excited van der Waals state, Mg(3p pi 3p pi P-3(J))center dot Kr[(3)Sigma(-)]

The unusual doubly excited van der Waal's state, Mg(3 p pi 3 p pi P-3(J)).Kr[(3)Sigma(-)], has been characterized using a laser-vaporization, supersonic-jet source and R2PI (Resonance Two-Photon Ionization) spectroscopy. This state is very strongly bound (D-e,= 3966 cm(-1)) and has a short bond length (R-e = 2.45 Angstrom) compared to its singly excited analogue, Mg(3 s 3 p pi P-3(J)).Kr[(II0)-I-3-], for which D-e = 267 cm(-1) and R-e = 3.48 Angstrom. In fact, this state is even more than twice as strongly bound as the ground-state Mg(3s)(+).Kr ion, where D-e = 1949 cm(-1) and R-e approximate to 2.8 Angstrom. Possible reasons for the strong van der Waal's bonding are discussed, and it is concluded that the lack of sigma-sigma repulsion because there is no Mg(3s sigma) valence electron must be a major factor; the similar ionic van der Waal's state Mg+ (3p pi).Kr[(II)-I-2], which would be obtained by removing one of the Mg(3p pi) electrons, is even more strongly bound, with D-e approximate to 7200 cm(-1) [J. S. Pilgrim, C. S. Yeh, K. R. Berry, and M. A. Duncan, J. Chem. Phys. 100, 7945 (1994)

Spectroscopic characterization of the Zn(4s(2))center dot Ne[(1)Sigma(+)] and Zn(4s4p pi)center dot Ne[(1)Pi(1)] van der Waals states

The Zn(4s2)·Ne[1Σ+] and the Zn(4s4pπ)·Ne[1Π1] states have been characterized by laser-induced fluorescence spectroscopy. Bond lengths were determined from simulations of the partially-resolved rotational structure of the 1Π ← 1Σ+ transitions, while bond strengths were estimated from a Birge–Sponer extrapolation with allowance for consistent errors resulting from similar procedures in the analogous Cd·Ne and Hg·Ne transitions. The van der Waals bonding in these states is discussed briefly and compared to that in the analogous M·RG states, where M=Mg, Zn, Cd, Hg and RG=Ne, Ar, Kr, Xe

Spectroscopic characterization of the Zn(4s(2))center dot Ne[(1)Sigma(+)] and Zn(4s4p pi)center dot Ne[(1)Pi(1)] van der Waals states

The Zn(4s2)·Ne[1Σ+] and the Zn(4s4pπ)·Ne[1Π1] states have been characterized by laser-induced fluorescence spectroscopy. Bond lengths were determined from simulations of the partially-resolved rotational structure of the 1Π ← 1Σ+ transitions, while bond strengths were estimated from a Birge–Sponer extrapolation with allowance for consistent errors resulting from similar procedures in the analogous Cd·Ne and Hg·Ne transitions. The van der Waals bonding in these states is discussed briefly and compared to that in the analogous M·RG states, where M=Mg, Zn, Cd, Hg and RG=Ne, Ar, Kr, Xe

Two-electron pseudopotential investigation of the electronic structure of the CaAr molecule

International audienceThe electronic structure of the Ca-Ar molecule is investigated using [Ca2+] and [Ar] core pseudopotentials complemented by core polarization operators on both atoms, considering the molecule to be a two-electron system. The electronic two-body problem is solved by achieving a full configuration interaction with extensive Gaussian basis sets. The potential energy curves and the molecular constants of all CaAr states dissociating into atomic configurations ranging between the ground state 4s2 1S and the doubly excited state 4p2 3P are determined. Spin-orbit coupling is also included in an atom-in-molecule scheme for states dissociating into the 4s4p and 4s3d configurations. The present theoretical results show good overall agreement with experimental data. They also help to clarify the very complicated spectroscopy of the CaAr system in the 38 000 cm-1 energy range where many states correlated with the 4s4d, 3d4p, and 4p2 atomic configurations interact with or cross one another. As a by-product of the present investigation and with the purpose of checking the pseudopotential accuracy on a simpler related system, low-lying potential energy curves of the single active electron CaAr+ ion are also reported and the corresponding molecular constants are compared with the existing literature

Accurate potential energy curves for Zn+-Rg (Rg = He-Rn): Spectroscopy and transport coefficients

High-quality ab initio potential energy curves are presented for the Zn+–Rg series (Rg = He–Rn). Calculations are performed at the RCCSD(T) level of theory, employing aug-cc-pV5Z quality basis sets, with ‘small core’ relativistic effective core potentials being used for Kr–Rn. We present spectroscopic information for the titular species, derived from our potential energy curves, and compare to previous results. We also present calculated ion transport data and show that mobility minima occur for a number of these systems, albeit at low gas temperatures for some of them