He–He chemical bonding in high-frequency intense laser fields

Abstract

On the basis of the Kramers-Henneberger (KH) high-frequency approximation, we carried out an ab initio molecular orbital calculation for He 2 in intense laser fields. The potential energy curve is found to be attractive, indicating that a He-He chemical bond is formed. The formation of the He-He chemical bond is ascribable to changes in the nature of KH molecular orbitals. Intense laser fields cause a kind of sp hybridization of KH atomic orbitals. The degree of the hybridization depends on the internuclear distance, and reaches a maximum at around the equilibrium internuclear distance. This hybridization remarkably strengthens/weakens the bonding/anti-bonding character of the 1σ g /1σ u KH molecular orbitals, respectively.

Analytic approach for controlling quantum states in complex systems

“…The amplitude of the pulse becomes smaller when the target time T is larger since an effective pulse area should be a constant π [29]. Although our controlled dynamics seems to be antithetical to the molecular processes induced by intense laser fields [33,34], this does not necessarily mean that our approach is not applicable to those systems. This is because such dynamics driven by the intense laser field can be included in the "unperturbed" Hamiltonian H 0 .…”

Positronium in superintense high-frequency laser fields

“…These qualities predict that, for any system that fulfils the HFFT validity criteria, the ionisation rate will decrease as the radiation intensity increases. In applications of HFFT to atoms and molecules, this counterintuitive inhibition of ionisation has attracted considerable attention over the past two decades [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27], yet it seems not to have been explicitly evaluated for Ps atoms.…”

The absorption spectrum of the (1,0), (3,1) and (4,2) bands in the c3Σg+–a3Σu+ system of He2 eximer

“…It is the simplest but the most studied exemplary both in experiments and in theory. The He 2 molecule plays a significant role in the fields of chemical bond formation [1][2][3], the mechanism of low-temperature discharge plasma [4,5] and the spectroscopic study of superfluid helium nano-droplets [6,7].…”

“…In 1965, Ginter [9] studied the emission spectra in the c 3 R g + -a 3 R u + system using grating measurements, and nine bands (i.e., (0, 0), (1, 0), (2, 0), (1, 1), (2, 1), (3,1), (2,2), (3,2) and (4, 2) bands) were studied, which resulted in a set of molecular constants. In the late 1970s, Vierima and his coworkers [10,11] investigated the fine structure of spin-spin and spin-rotation interactions of the a 3 R u + state by employing highly precise magnetic resonance radio-frequency spectroscopy, and thus, the fine structural parameters for the N = 1 and 3 rotational levels of the t = 0 level were obtained.…”