Absorption intensities of the multipole-field-induced zero-phonon transitions in solid HD, HT, and DT

Abstract

Closed-form theoretical expressions are derived for the integrated absorption coefficient of various zerophonon single and double transitions in heteronuclear isotopic variants of hydrogen in condensed phase. Theoretical analysis predicts a different kind of double transition in the spectra of solid HD, HT, and DT, where the rotational energy of one molecule changes by three quanta and the rotational energy of another molecule simultaneously changes by at least three quanta. The expressions for double transitions given in this paper may, for example, be applied to double transitions involving para-H 2 -HD or ortho-D 2 -HD pairs.

Effect of orthohydrogen impurity on the absorption intensities of single transitions in a solid parahydrogen crystal

“…is approximately 12 for all ' [18], showing clearly that the contributions are dominated by the nearest neighbors. Note that S d (') is a positive definite sum and is free from any cancellation effect.…”

“…(1) and (2) are to be multiplied by the appropriate phonon renormalization factors n 2 s or n d , which correct the rigid lattice sums for the zero-point motions [13][14][15][16][17][18][19][20]. The phonon renormalization factors are not easily amenable for calculations, a priori and it is customary to set them equal to unity.…”

“…In solid hydrogen, since the transitions originate due to multipolar induction, the internal energy of a single molecule (single transition) or a pair of molecules (double transitions) is changed upon absorption of a single photon. The expressions for the intensity of single and double transitions involve sums over the entire lattice [13][14][15][16][17][18][19][20]. In case of single transitions, the lattice sums are affected by the cancellation effect due to crystal-symmetry.…”

“…Study of absorption intensity of multipole field-induced transitions in solid hydrogen has provided, over the years, a fundamental testing ground for both theory and experiment [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In solid hydrogen, since the transitions originate due to multipolar induction, the internal energy of a single molecule (single transition) or a pair of molecules (double transitions) is changed upon absorption of a single photon.…”

Absorption intensities of the multipole-field-induced double transitions involving a homonuclear-heteronuclear pair of hydrogen molecules in condensed phase

“…Recently, while developing intensity formulas for multipole-induced transitions in solid HD, HT, etc., we realized that most of the expressions for double transitions can be applied to mixed double transitions involving para-H 2 -HD or ortho-D 2 -HD pairs. 22 The goal of this paper is to present intensity expressions derived for mixed isotopomer transitions involving ortho-H 2 or para-D 2 (Jϭ1) in the molecular pair. Here J refers to the rotational quantum number of the molecule.…”