Quantification of distortion of the water OH-band using picosecond Raman spectroscopy

Abstract

An anomalously large (~40 cm−1) blue-shift of the Raman OH stretching vibration band was observed when bulk water was probed by picosecond versus nanosecond pulses. The temperature distortion of the OH band contour (3200–3600 cm−1) was studied by both nanosecond and picosecond Raman techniques. It was observed that the OH band centroid shifted linearly with temperature (~0.87 cm−1 °C−1) for both nano- and picosecond pulses. This feature of the picosecond Raman spectra was explained by the dynamics of the non-equilibrium hydrogen bond structures in water.

Asymmetric broadening and blue shift of the stimulated Raman scattering spectrum in water under chirped picosecond laser pulse train excitation

“…For each pump train length (2-3, 7, 15, 25 pulses), three spectra of the SRS Stokes component were recorded sequentially. Note that centroids of all the SRS spectra are concentrated in the vicinity of the spontaneous Raman OH band extremum (3360-3420 cm −1 , dashed line in figure 2(b)) from work [11]. This coincidence highlights the most probable density of spectral states in water at room temperature.…”

“…To check the negative chirp influence on the observed SRS OH band narrowing and splitting we measured water SRS spectra under 15 ps non-chirped single pulses excitation at 527 nm with 30 cm −1 pump line FWHM [11]. The typical spectrum of the SRS Stokes component is presented in figure 2(a) (dashed line).…”

“…Indeed, the OH band centroid blue shift by ∼35 cm −1 (figure 3(b), circles) could be explained by the heating of water in the beam waist volume when picosecond pulse train length is increased. Earlier [11], we measured the coefficient (∼0.87 cm −1 • C −1 ) of spontaneous Raman OH band centroid linear shift for nano-and picosecond pulse excitation. Such centroid shift occurs due to the destruction of large hydrogenbonded complexes when water is heated by an external source.…”

“…Given that the molecular complexes in water rearrangement time is finite and is limited by the switching time of hydrogen bonds (∼1 ps), one can expect that non-stationary complex formation processes would manifest themselves in the Raman OH band envelope deformation while decreasing the duration of probing pulses. Indeed, a reduction in the duration of pump pulses by almost three orders of magnitude (from 10 ns to 15 ps) [11] led to a shift of the OH band centroid by ∼40 cm −1 towards the high-frequency wing. This shift indicated an increase in the contribution of high-frequency OH oscillators (small-sized complexes) under non-stationary conditions.…”

Study of the Magnetic Water Treatment Mechanism

“…The presence of ortho-and a para-spin isomers of water in different rotational states was established with different methods in [Horke, et al, 2014;Mamrashev, et al, 2018;Kravchuk, et al, 2011;Hama, et al, 2016;Pershin, et al, 2018;Kilaj, et al, 2018]. An aqueous solution is a complex system of molecular complexes with a variable configuration of structural bonds and monomers that differ in the quantum and physical properties.…”