Release Time:2019-03-09  Hits:

Indexed by: Journal Article

Date of Publication: 2014-01-01

Journal: LASER PHYSICS

Included Journals: Scopus、EI、SCIE

Volume: 24

Issue: 1

ISSN: 1054-660X

Key Words: molecular orientation; the single-cycle THz pulse; the rigid-rotor model

Abstract: We theoretically study the field-free orientation dynamics of CO molecules in three cases, with the orientation steered (I) by a single-cycle THz pulse, (II) by a single-cycle THz pulse train L-1, and (III) by the combination of an off-resonant femtosecond pulse L-0 with L-1. In case (I), the strong intensity of the single-cycle THz pulse is required to realize efficient molecular orientation. In case (II), by using a pulse train L-1 with experimentally accessible intensity 1 MV cm(-1), the maximum orientation degree vertical bar < cos theta >vertical bar(max) = 0.906 is achieved when pulse number N = 25. In case (III), by introducing the Raman excitations of L-0, the pulse train L-1 with only N = 3 can realize a high degree of orientation, vertical bar < cos theta >vertical bar(max) = 0.896. Moreover, we investigate the dependence of the thermally averaged orientation on the initial rotational temperature in cases (II) and (III). The maximum orientation degree vertical bar << cos theta >>vertical bar(max) decreases with the increase of rotational temperature in the two cases. However, case (II) is more robust against the rotational temperature: vertical bar << cos theta >>vertical bar(max) > 0.5 can still be achieved when the rotational temperature is as high as T = 30 K.