Motion of hydrogen bonds in dilutedHDO/D2Osolutions: Direct probing with 150 fs resolution

Abstract

An experiment is described to study temporal variations of the hydrogen bond length in diluted HDO/D2O solutions. The principles of this laser spectroscopic experiment are explained first. The construction of a laser source generating 150 fs pulses in the 2.5-4.5 microns spectral region at a 10 microJ power level is detailed next. The OH stretching band is reproduced for different excitation frequencies and different pump-probe delay times. A theory, based on statistical mechanics of nonlinear optical processes, is proposed to calculate the lowest two spectral moments. An effect is reported, the delay dependent vibrational solvatochromism. It is shown how this effect can be exploited to follow temporal variations of the OH...O bond length directly, in real time. The corresponding time scales are of the order of 700 fs. No bond oscillations are observed.

Energy Transfer in Single Hydrogen‐Bonded Water Molecules

“…The structure and dynamics of the hydrogenbonded complexes were studied using linear mid-infrared spectroscopy and femtosecond mid-infrared pump-probe spectroscopy. [13][14][15][16][17][18][19] In both techniques, the system was studied via the response of the OÀH stretching vibrations of the H 2 O/HDO molecule. The linear absorption spectra were measured using a Perkin-Elmer spectrometer.…”

Vibrational Line Shapes, Spectral Diffusion, and Hydrogen Bonding in Liquid Water

“…The shoulder in the Raman spectra has been attributed to HOD molecules lacking a hydrogen (H) bond to the H atom [15][16][17][18][19]. Two-and three-pulse echo [10,[20][21][22][23][24][25][26] and other ultrafast [16,17,[27][28][29][30][31][32][33][34][35][36][37] experiments have also been performed on this system. One such integrated three-pulse echo peak shift experiment [10] shows an interesting oscillation at short times (with a period of about 180 fs) that has been attributed to underdamped H-bond stretching [15,23,[38][39][40][41][42], and a long-time decay on a 1.4-ps time scale that is thought to be due to dynamics of H-bond rearrangement [15,16,24,38,40,42,43].…”

Interplay of the Intramolecular Water Vibrations and Hydrogen Bond in N-Methylacetamide-Water Complexes: Ab Initio Calculation Studies

“…48 In order to study H-bond dynamics in the time domain, Gale et al used femtosecond IR pump-probe method to directly investigate the dynamics of H-bonds in liquid water. 49,50 Also, Nienhuys et al carried out a similar experiment for HDO : D 2 O solution. 51 Noting that the OH stretching mode frequency is sensitively dependent on the H-bond length, as found by Mikenda, 52 they were able to measure solvatochromic shift revealing real time dynamics of the H-bonds in liquid water.…”

“…[49][50][51] Tuning the pump field frequency to be resonant with one of the amide mode transitions as well as controlling the probe field frequency being resonant with one of the three water mode transitions, one can measure time-dependent evolution of the H-bond dynamics by using the relationships discussed in this paper. In this regard, the symmetric OH stretching mode of water molecules H-bonded to the NMA sites A and B can be the primary target for this type of experiment measuring equilibrium and/or non-equilibrium H-bond structures, because ω ss and its IR intensity were found to be a quickly varying function of the intermolecular distance.…”