Ne Van Der Waals Complexes Research Articles

High-resolution infrared spectra of H2–Ne and D2–Ne van der Waals complexes This article is part of a Special Issue on Spectroscopy at the University of New Brunswick in honour of Colan Linton and Ron Lees.

Spectra of weakly bound hydrogen–neon complexes have been studied in equilibrium gas mixtures at relatively high spectral resolution (0.05–0.12 cm–1) using a long-path (112 m), low-temperature (24 K) absorption cell and a Fourier transform infrared spectrometer. Most of the data cover the region of the H2 or D2 fundamental stretching vibrations in the mid-infrared (λ ∼2.4 or 3.3 μm), but results on the pure rotational S0 (0) band of D2–Ne in the far-infrared (λ ∼55 μm) are also included. The spectra are greatly improved compared to the only previous observation. The results serve as a stringent experimental constraint for testing and improving theoretical determinations of the potential-energy surface, which describes the intermolecular forces for the hydrogen–neon system.

Characteristics and relaxation dynamics of van der Waals complexes between p-difluorobenzene and Ne.

Characteristics of the single and double Ne van der Waals complexes of p-difluorobenzene (pDFB) have been explored with ultraviolet fluorescence excitation and dispersed fluorescence spectroscopy. Eight S(1)-S(0) fluorescence excitation bands involving six ring modes of pDFB-Ne and two bands of pDFB-Ne(2) have been identified. Band assignments are confirmed by dispersed fluorescence from the pumped band. Shifts of the complex bands from the analogous monomer bands are generally 4 cm(-1) to the red for pDFB-Ne and 8 cm(-1) for pDFB-Ne(2). None of the observed ring modes is significantly perturbed by complexation in either the S(1) or S(0) states. The pDFB-Ne S(1) van der Waals binding energy D(0')</=120 cm(-1) is inferred from fluorescence band assignments with D(0')-D(0")=4 cm(-1). Vibrational predissociation of pDFB-Ne to produce the S(1) monomer is observed after pumping several levels, but the dissociation process is generally slow compared to fluorescence decay of the complex. Dissociation of the double complex pDFB-Ne(2) occurs from one level to produce S(1) pDFB-Ne in its zero point level. Comparisons are made with the relaxation dynamics of the S(1) complexes pDFB-Ar and pDFB-N(2).

Coupled cluster calculations of the ground state potential and interaction induced electric properties of the mixed dimers of helium, neon and argon

Using augmented polarized correlation consistent basis sets extended with midbond functions, we evaluate the ground state interaction potential and the induced electric dipole polarizabilities and first and second hyperpolarizabilities of the He–Ar, Ne–Ar and He–Ne van der Waals complexes. For the calculation of the potential we resort to the coupled cluster singles and doubles (CCSD) model corrected for triple excitations, CCSD(T), whereas properties are evaluated with CCSD response theory. As a check of the quality of the potential, the rovibrational spectrum and the gas second virial coefficients are evaluated. The rovibrational spectra improve previously available theoretical results, although the dissociation energies are probably still slightly underestimated. For the gas second virial coefficients the agreement with experiment is satisfactory. The frequency dependence of the interaction (hyper)polarizabilities is analysed and a comparison with previous results on the mixed dimers and the pure gases is made.

Potential curves for the ground states and some excited states of MgNe, Mg+Ne, and Mg+2Ne van der Waals complexes

We have estimated the potential curves of the Mg(3s2)⋅Ne(1Σ+), Mg(3s3p)⋅Ne(3Π,3Σ+), Mg(3p2)⋅Ne(3Σ−), Mg+(3s)⋅Ne(2Σ+), Mg+(3p)⋅Ne(2Π), and Mg+2(2p6)⋅Ne(1Σ+) van der Waals states by means of ab initio calculations. Similar to the analogous doubly-excited states of MgAr and MgKr, the Mg(3pπ3pπ)⋅Ne(3Σ−) state is found to be unusually strongly bound, De=548 cm−1, a bond strength which is more than 20 times that of the singly-excited Mg(3s3pπ)⋅Ne(3Π) state and even more than three times that of the Mg+(3s)⋅Ne ion. The strong bonding is attributed primarily to the lack of a Mg(3s) electron, so that all the attractive van der Waals forces can extend to smaller internuclear distances because there is no Mg(3sσ)/Ne(2pσ) exchange repulsion.

Spectra of H2–Ne and D2–Ne Van der Waals Complexes in the Collision-Induced Fundamental Bands of Hydrogen and Deuterium

Spectra of H2–Ne and D2–Ne Van der Waals complexes accompanying transitions in the collision-induced fundamental bands of hydrogen and deuterium have been obtained with an absorption path of 110 m at temperatures around 27 K in a specially designed multiple-traversal cell. The observed structure is similar to that of H2– and D2–Ar, Kr, and Xe complexes studied earlier, but the number of lines observed for the Ne complexes is fewer because of the shallower intermolecular potential. Well-resolved R and P branches (Δl= ±1, where l is the rotational quantum number of the complex) accompanying the overlap-induced Q1 (0) transitions are analyzed directly to give rotational (B) and centrifugal stretching (D) constants for the complexes. Unlike the other H2– rare gas complexes the spectra accompanying quadrupole-induced transitions show no direct evidence of anisotropy of the intermolecular forces.