Anisotropy of the hypersonic grating and spectra of four-photon Rayleigh-line-wing spectroscopy in water

A model describing the Rayleigh-line-wing spectra obtained in water by four-photon polarized spectroscopy is proposed. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 5, 411–413 (10 March 1997)     

The temperature dependence of the Rayleigh line wing and depolarized combinational scattering line widths in critical mixtures

It has been experimentally found that at approaching the critical temperature of the exfoliating mixture carbon-disulfide-ethanol the widths of the Rayleigh line wing and the depolarized combinational scattering line drastically decrease. The same phenomenon was observed for 3 nitrobenzene combinational line scattering in a nitrobenzene—n-hexane mixture.     

Origin of low-frequency spectrum structure of four-photon scattering in liquid water

-1 has been found experimentally in liquid water. The theoretical interpretation relates these spectral features to an interference of strictional and orientational contributions to the scattered signal. Received: 16 October 1996     

Comments on “the Rayleigh line wing and the coefficient of depolarization of scattered light in critical mixtures”

Independent measurements of the linewidth of the depolarized Rayleigh line in the critical mixture of nitrobenzene and n-hexane, persistently disagree with each other. We thus analyse here the limitations of the experimental methods and show that the strong critical narrowing observed by Fabelinskii et al. is probably an experimental artefact.     

Interference-free UV-laser-induced Raman and Rayleigh measurements in hydrocarbon combustion using polarization properties

It is demonstrated that precise spontaneous Raman scattering measurements with deep-UV lasers are in principle possible in hydrocarbon flames - even with liquid fuels - by the use of polarization properties. In contrast to the highly polarized Raman emission, the strong interfering broadband emission from combustion intermediates is unpolarized. Subtracting the emission intensities for the electric vector of the laser light perpendicular and parallel to the direction of observation allows to extract the pure Raman signals. Different applications of this technique are discussed.     

Investigations of the structure of water using mid-IR fiberoptic evanescent wave spectroscopy

Liquid water is one of the most studied but still one of the least understood substances. The absorption spectra of water in the mid-IR were measured from -10 and up to 90 degrees C using fiberoptic evanescent wave spectroscopy. The changes in the spectrum and the existence of an isosbestic point during the ice-liquid phase transition were studied. Based on the spectroscopic data we propose a multispecies model for the structure of liquid water. The new model provides an explanation for the results of the measurements reported in this work. It also provides an explanation for some of the unique thermodynamic and kinetic properties of liquid water and for many of the anomalies of water.     

Observation of rotational resonances of ortho and para spin isomers of the H<Subscript>2</Subscript>O molecule in hexagonal ice using four-photon laser spectroscopy

Rotational resonances of ortho and para spin isomers of the H₂O molecule are observed in hexagonal ice using four-photon spectroscopy of coherent light scattering. It is experimentally shown that the resonant contribution to the four-photon scattering signal from para H₂O spin isomers in ice is about half as large as that in the liquid phase.     

Four-photon polarization spectroscopy of water in a millimeter-wave radiation field

Resonance (frequency 1.4 cm⁽⁻¹) changes induced in the four-photon optical spectrum of water by a millimeter-wave electromagnetic field are observed experimentally. Comparison with the spectrum of ice in the range 0‒2 cm⁽¹ shows that the action of such a field is of a structure-forming character. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 4, 266–268 (25 August 1998)     

Four-photon laser spectroscopy of translational vibrations of a proton in water and hexagonal ice

For the first time, translational vibrations of a proton in H₂O, D₂O, HDO, and hexagonal ice were found in the Rayleigh line wing using four-photon polarization spectroscopy.     

Temperature evolution of the relative concentration of the H2O ortho/para spin isomers in water studied by four-photon laser spectroscopy

The four-photon laser spectroscopy of molecular motions [1] of distilled water in the terahertz and subterahertz spectral ranges is employed to observe resonant lines related to the rotational transitions of ortho and para nuclear spin isomers of the H₂O molecule. It is demonstrated that the intensity ratio of the lines of the H₂O ortho/para spin isomers in several water samples decreases by a factor of 2.0–2.5 in comparison with the gas-phase ratio. A violation of the equilibrium ortho/para ratio upon the condensation of vapor is interpreted as a manifestation of the spin selectivity in the formation of the H-bonded complexes of the H₂O para isomers. The nonequilibrium ortho/para ratio characterizes water at room temperature as an unstable liquid with respect to the spin temperature.     

Solid-state NMR spectroscopy using the lost I spin magnetization in polarization transfer experiments

A variation of the cross polarization (CP) experiment is discussed. The method requires two scans where the difference signal is equivalent to the I spin magnetization that is transferred to the S spins. The acquired signal is equivalent to F1 sum projection of a two-dimensional (2D) heteronuclear correlation experiment and is obtained by just two scans without the need to increment the indirect time domain t(1). Any polarization transfer method and any kind of spin manipulations during the t(1) incrementation period of a 2D NMR experiment can be applied. The method allows fast measurements of the CP transfer, particularly if various S spins signal overlap and is good for spectral editing of I spin signals with contact to S spins. Various examples for biomaterials are presented. Most importantly, this novel approach is ideal for detailed investigations of organic-mineral interfaces in bone, here demonstrated for O-phospho-l-serine as simple model compound.     

基于飞秒激光等离子体丝诱导击穿光谱探测土壤重金属Cr元素含量

本文基于飞秒激光等离子体丝诱导击穿光谱对土壤重金属Cr元素含量进行了实验研究.利用荧光法对等离子体丝的长度进行测量,给出了在不同焦距聚焦透镜作用下土壤中Cr425.5 nm的谱线强度空间分布,实验给出了Cr元素的定标曲线.实验结果表明,土壤中Cr元素浓度分析测量的相对标准偏差小于5%,土壤中重金属Cr元素的检测极限为7.85 ppm.表明飞秒激光等离子体丝诱导击穿光谱技术在土壤重金属Cr元素含量的定量探测方面是完全可行的.     

Analysis of the first electron-removal states of using polarization dependent angle-resolved photoelectron spectroscopy

The first electron-removal states of the layered cuprate Ba₂Cu₃O₄Cl₂ were measured using angle-resolved photoelectron spectroscopy. The symmetry and energy-momentum relations of the lowest-lying states were determined and interpreted in terms of the motion of a single hole in the two different planar Cu-O subsystems of the Cu₃O₄ plane. One subsystem is antiferromagnetic as in the undoped parent compounds of the high-temperature superconductors and the other is paramagnetic and corresponds to the strongly overdoped case. The data are compared to theoretical results on hole dynamics in two-dimensional antiferromagnetic or paramagnetic spin backgrounds. The lineshape, symmetry and dispersion of the first electron-removal states of Ba₂Cu₃O₄Cl₂ can be described in terms of Zhang-Rice singlets within a single band model. The photohole lifetime in the paramagnetic subsystem of the Cu₃O₄ plane is much smaller than with an antiferromagnetic spin background. Received 19 March 1999 and Received in final form 15 August 1999     

Standoff detection of large organic molecules using Rydberg fingerprint spectroscopy and microwave Rayleigh scattering

We present a technique for nonintrusive and standoff detection of large organic molecules using coherent microwave Rayleigh scattering from plasma produced by structure sensitive photoionization through Rydberg states. We test the method on 1,4-diazobicyclooctane. Transitions between the 3s Rydberg state and higher lying Rydberg states are probed using two-color photoionization with 266?nm photons and photons in the range of 460-2400?nm. Photoionization is detected using microwave radiation, which is scattered by the unbounded electrons. Highly resolved Rydberg spectra are acquired in vacuum and in air.     

Zeeman effect in the polarization spectroscopy of Na

The Doppler-free polarization spectrum of the D₁ line has been studied in fields of about 50 G and in zero field. Although the principal Zeeman resonances are resolved, the signals are confusing because of the very large number of cross-over resonances. Cross-over resonances also seriously distort well-resolved resonances in zero field. An interpretation is given, based on combining a first-order theory of optical pumping with the theory of Faraday rotation and dischroism.     

Detection of phase transitions in heavy silane by i.r. spectroscopy

An i.r. spectroscopic study of SiHD₃ isolated in SiD₄ reveals an apparent second-order phase transition at 38 K. In the lowest-temperature phase the SiD₄ molecules probably occupy two sites of C₁ symmetry. Between 38 K and 67 K the SiD₄ molecules probably occupy one site of C_s symmetry.