Ultrafast motion of liquids C2H4Cl2 and C2H4Br2 studied with a femtosecond laser

Study of picosecond nonlinear refraction in C2H4Cl2 and C2H4Br2 with Z-scan technique

“…4 shows the comparison of the fs RIKE spectra of thee intermolecular dynamics for C2H4Cl2 and C2H4Br2. Obviously, C2H4Br2 exhibits a stronger strength than that of C2H4Cl2 in each category [6]. This explains that n2 determined by ps Z-scan is stronger in C2H4Br2 than in C2H4Cl2.…”

Study of Negative Lensing Effect in Transparent Molecular Liquids by Femtosecond Laser Pulses

“…The preliminary results of nonlinear refractions n 2 of C 2 H 4 Cl 2 and C 2 H 4 Br 2 are found to be cm 2 /W and cm 2 /W, respectively. To explain why the nonlinear refraction sign is opposite to that obtained with 10 Hz ps and ns pulses, two possible mechanisms are invoked in light of previous studies of time resolved Raman induced Kerr effect (RIKE) on a variety of simple transparent molecular liquids [3][4][5] and thermal lensing effect [8,9]. According to our previous time resolved RIKE study, the occurrence of electronic and resonant nuclear motions takes tens of fs; however, that of the non-resonant nuclear motions takes hundreds of fs, considerably longer than a 28 fs pulse.…”

“…We attributed this lensing effect to the third-order polarization originating from resonant responses of molecular skeletal motions, which are electrostatically coupled to the valence electron cloud distorted by the fs laser field. Of various kinds of nonlinearly driven skeletal motions studied with the fs optical Kerr effect (OKE) [3][4][5] we invoke librational and vibrational resonance to account for the negative lensing effect manifested in the Z-scan signals of two compounds studied. This result may be expected whenever a single, sufficiently short laser pulse passes through many types of Raman-active media, as implied by impulsively simulated Raman scattering [6], in which the change in light intensity is associated with a red shift in the excitation pulse spectrum.…”

Thermal lensing effect of CS2 studied with femtosecond laser pulses

“…According to previous studies of the time-resolved optical Kerr effect (OKE) [10][11][12][13][14][15][16][17][18][19][20][21][22][23] in a variety of simple liquids, resonant excitations of both intra-and inter-molecular motions, in addition to non-resonant excitation of electronic motion, can be fulfilled by fs laser pulses via various SLS processes (third-order nonlinear optical responses to the fs laser pulses). Excitation of each molecular motion by means of a specific SLS process promotes individual molecules from state |0) m to state |1) m , via an intermediate virtue state, by absorbing a photon at angular frequency o 1 and emitting a photon at angular frequency o 2 with (o 1 À o 2 ) falling within the range [O m À DO m /2, O m + DO m /2].…”