Radical-Recombination Luminescence of the Uranyl Nitrate Complex in the Adsorbed State

We have investigated the luminescence of uranyl nitrate molecules on the surface of powdery SiO₂ upon excitation by UV light (PhL) and hydrogen atoms (radical-recombination luminescence (RRL)). It has been found that the PhL and RRL spectra have a clearly defined vibrational structure. The luminescence peaks of the adsorbed UO₂ ^2– ion are characterized by a systematic longwave shift from the same peaks of crystalline uranyl nitrate (by 230–430 cm^–1 at 130 K). Moreover, in the adsorption centers the vibration frequencies of UO₂ ^2– are 20–80 cm smaller than in crystalline salt and the RRL bands are 150–350 cm^–1 (130 K) wider than the corresponding PhL bands.     

Estimation of the Optimum Concentration Interval of the Contents of Praseodymium, Neodymium, Europium, Holmium, and Erbium in a Solution

Based on the electronic absorption spectra of Pr³⁺, Nd³⁺, Eu³⁺, Ho³⁺, and Er³⁺ ions in 1 M aqueous solutions of chloric acid, calibration graphs have been constructed in a concentration of metals–optical density of a solution format for different frequencies. The band for praseodymium was used at 22,520 cm^–1, for neodymium at 17,380, 13,480, and 12,560 cm^–1, for europium at 25,380 cm^–1, for holmium at 18,580 and 15,580 cm^–1, and for erbium at 39,160, 26,480, and 19,160 cm^–1. The errors in determining the concentration of the indicated elements as a function of their content have been calculated. It is shown that for perchloric solutions of praseodymium it is possible to correctly determine its contents within the concentration range 0.1–1.5% at a frequency of 22,520 cm^–1; for neodymium the ranges are 0.4–1.0, 0.3–1.0, and 0.5–1.0% at 17,380, 13,480, and 12,560 cm^–1, respectively; for europium 0.4–1.5% at 25,380 cm^–1; for holmium — 0.2–1.5 and 0.4–1.5% at 15,580 and 18,580 cm^–1, and for erbium the range is 0.4–1.0% at frequencies of 39,160, 26,480, and 19,160 cm^–1.     

The IR absorption spectrum of 2 - aminothiazolid - 4 - one

A mechanical model has been used to calculate the frequencies in the vibrational spectrum of the imine and amine tautomeric structures for this compound; the IR spectrum for the crystalline state has been deduced for the range 80–3500 cm^–1, and a discussion is given for the effect of the tautomeric prototropic forms on the vibrational spectrum.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 9, pp. 76–82, September, 1971.     

Theoretical calculations and Raman spectrum of intercalation modes in LixInSe

By using an extended linear-chain model which includes the interlayer forces, we have calculated the new vibrational modes, of Li intercalated InSe. The dispersion curves along thek _z wavevector perpendicular to the layers for the -polytype are determined in the first Brillouin zone. Assuming that the interlayer interaction is not modified upon intercalation and the interaction between lithium atom and adjacent layers in the van der Waals plane has the same value than the interlayer one, the new modes are determined with the force constant given by the rigid layer mode of the, -polytype at 18 cm^–1. This model gives the variation of the acoustic branches and the appearance of two optical intercalation modes at higher frequencies. The Brillouin zone boundary modes of the acoustic branches at 18 and 41 cm^–1 in the pure material are calculated to be 22 and 50 cm^–1 respectively forx=1/2. The dispersion of the new optical branches is flat along thez-direction and frequencies are obtained at 96 cm^–1 for the Li mode perpendicular tok _z and at 218 cm^–1 for the Li mode parallel tok _z. We compare also our results with the Li mode frequencies obtained in a total energy calculation. Raman scattering experiments have been performed in intercalated sample in order to verify the proposed model.     

Anharmonic resonances in the vibrational spectra of pyrazine

The quartic force field of pyrazine has been calculated in the B3LYP/6-31G(d) hybrid density-functional approximation. Based on the results of this calculation, the total IR (250–3800 cm^–1) and Raman (400–3200 cm^–1) spectra of pyrazine have been interpreted with consideration for the Fermi and Darling-Dennison resonances and their spectral manifestations. A precision method is proposed for anharmonic analysis of the vibrational states of polyatomic molecules on the basis of consideration of their theoretical anharmonicity constants in combination with the corresponding experimental frequencies. The method of linear scaling of frequencies has been theoretically substantiated.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 1, pp. 13–22, January–February, 2005.     

The LIF Excitation Spectrum of Jet-Cooled 2,6-Dicyano-3, 5-Dimethylaniline

The laser-induced fluorescence (LIF) excitation spectrum of jet-cooled 2, 6-dicyano-3,5-dimethylaniline (DCDMA) has been measured in the spectral range of 29,750–32,250cm^–1. The band origin at 29,860.8 cm^–1 and as many as 250 vibrational bands have been identified in the excitation spectrum. The analysis of the excitation spectrum of DCDMA gives more than 28 vibrational modes involving aromatic ring oscillations and oscillations related to the substituent groups. DCDMA is nonplanar in the ground state, with the NH₂ plane at about 9° with respect to the molecular plane (RHF/6-31G*). The singlet excited molecule is planar (CIS/6-31G*). Both CIS/6-31G* and CASPT2 calculations predict that the lowest excited state of DCDMA involves a dominant HOMO-LUMO excited configuration. The characteristic feature of the excitation spectrum of DCDMA is the presence of progressions in the low-frequency mode, 112 cm^–1. The calculations suggest that this mode and some other active modes involve motions of the amino group and strongly interacting adjacent cyano substituents.     

Optical studies on free-standing polypyrrole films by the photopyroelectric method

Optical spectra of free-standing polypyrrole films were investigated by a novel PhotoPyroElectric (PPE) method. The reflection and absorption spectra in the range 2000–25000 cm^–1 of TsO^–- and ClO ₄ ^su– -doped polypyrrole films were obtained with an experimental setup comprising two pyroelectric sensors. The absorption bands due to electronic transitions to the bonding and antibonding bipolaronic levels appear at 11 000 and 21 500 cm^–1, respectively. Some relevant details in the polypyrrole spectrum in the 2000–5000 cm^–1 range were observed. The absorption band located at 3400 cm^–1 is characteristic for NH stretching vibration. The bands in the 2300–2500 cm^–1 range are ascribed to the vibration of N⁺H groups containing positively charged nitrogen. The PPE spectra also reveal changes of the electronic and vibrational absorption bands after polymer reduction and HCl treatment.     

Infrared spectra of urine from cancerous bladders

The infrared spectra of organic constituents of urine from cancerous bladders of some patients were recorded. The spectra of the organic part of the samples were classified into five types according to the bulk constituents. Samples with type A spectra consisted mainly of proteins with only trace amounts of lipids. Their spectra were characterized mainly by the absorption bands of proteins at the frequencies 3330, 3075, 2960, 2850, 1650, 1530, 1450, 1400 and 1320 cm^–1, in addition to a weak band at 1720 cm^–1 due to the absorption of lipids. Samples with type B spectra were characterized by high amounts of proteins and low amounts of lipids and phosphate compounds. The presence of phosphate compounds was indicated by the absorption bands at the frequencies 1100 and 1030 cm^–1. Samples giving spectral type C were characterized by high urea contents as indicated by the presence of two strong bands at 1670 and 1630 cm^–1. Samples with the spectral type D consisted of urea and phosphate compounds whereas the last spectral type E consisted mainly of calcium oxalates, uric acids and phosphate compounds. The presence of calcium oxalates was indicated by the presence of its diagnostic bands at the frequencies 1630 and 1330 cm^–1, while the presence of uric acid was indicated by the bands at the frequencies 1360, 1130, 1020 and 880 cm^–1. On the other hand, the spectra of the organic part of urine from some normal bladders exhibited the characteristic bands of urea only.Careful examination of the spectra of the inorganic part of urine revealed that some samples consisted mainly of hydroxyapatite. The absorption bands of hydroxyapatite appeared at the frequencies 568, 603, 985, 1037 and 1128 cm^–1. The spectra of other samples showed that the bands of basic phosphates at the frequencies 568, 620, 727, 890, 1035 and 1140 cm^–1. The spectra of the inorganic part of urine from a number of normal bladders displayed the bands of basic phosphates. The relationship between urine constituents and pathological types of bladder tumor tissue was discussed.     

Study of processes of translational,rotational, and vibrational relaxation based on CARS spectra line shapes

This paper reviews the various physico-chemical processes responsible for actual linewidths encountered in high-resolution coherent anti-Stokes Raman spectroscopy (CARS). Most of the experimental data are based on linewidth measurements using a pulseamplified CARS spectrometer with an emission bandwidth (FWHM) of 2×10^–3 cm^–1. Detailed rotational and vibrational relaxation constants have been obtained from the analysis of theQ-branch profiles of C₂H₂, N₂, CH₄, and SiH₄.     

High-resolution synchrotron far-infrared spectroscopy of acrolein: The vibrational levels below 700 cm

The far-infrared spectrum of acrolein, CH₂CHCHO, is studied in the 100–360 cm⁻¹ region using continuum radiation from a synchrotron source. The combination of a very high resolution spectrometer, a long absorption path, and a low sample pressure, yields observed line widths of less than 0.0008 cm⁻¹. Observation of the ν₁₈ (157.9 cm⁻¹), and ν₁₃ (323.8 cm⁻¹) fundamental bands, together with six hot bands in the same regions, gives information on eight low-lying vibrational states of the molecule, including the Fermi and Coriolis interactions among them. Combining the present assignments with previous data on the ν₁₂ (564.34 cm⁻¹) and ν₁₇ (593.08 cm⁻¹) fundamental bands, all ten excited vibrational levels below 700 cm⁻¹ are analyzed in terms of one 1-state fit, two 2-state fits, and one 5-state fit.     

Microwave and low-frequency vibrational spectra of bullvalene

The microwave spectrum of bullvalene has been investigated in the region 18–40 GHz. In addition to transitions in the ground vibrational state, transitions arising from five excited vibrational states below 600 cm⁻¹ have also been observed. A combination of microwave intensity measurements and infrared and Raman data has been utilized to assign these vibrations. Three of the vibrations are E-type modes at 241, 355, and 588 cm⁻¹. One is an A₁-type mode at 445 cm⁻¹, and another is an A₂-type at 266 cm⁻¹. The microwave spectrum indicates the presence of a first-order Coriolis interaction for the E modes at 241 and 588 cm⁻¹. The first-order Coriolis coupling constant q = 0.557 MHz for the 241 cm⁻¹ vibration. The spectral results are consistent with C_3v symmetry for bullvalene.     

XeCl-laser-generated ablation products from a nitrogen-rich polymer studied by laser-ionization mass spectrometry

Laser-ionization time-of-flight mass spectrometry has been used to probe laser-ablation products from a nitrogen-rich polymer at a wavelength of 308 nm. The ablation products at a laser fluence of 150 mJ/cm² showed, similar to 532 nm ablation studied previously [18], two strong peaks due to neutral species that were assigned to C⁺ and CN⁺, as well as several weak peaks that were assigned to CH⁺, HCN⁺, HCNH⁺, H_nN–CN⁺ (n=1–3), and H₂N–C=N–CN⁺ or H₂N–C=N–CN⁺. The ablation products at 870 mJ/cm² revealed, in addition to a broad signal due to ionic products generated directly by the ablation laser, several peaks due to neutral products that were assigned to C⁺, C ₂ ⁺ , C ₃ ⁺ , CN⁺, HCN⁺, HCNH⁺, and NCCN⁺. The most probable flight velocities for major neutral products are 5.7×10⁴ cm/s at 150 mJ/cm² and 2.3–2.7×10⁴ cm/s at 870 mJ/cm². The results at a laser fluence of 150 mJ/cm² support the finding that the translational energy of the tragments has importance for the collision-induced product generation in the laser plume, as suggested earlier [18]. Furthermore, the product generation at 870 mJ/cm² is interpreted by the ejection of small neutral and ionic fragments, and subsequent reactions among the fragments.     

Torsion-rotation far-infrared spectrum of O-18 methanol

High-resolution Fourier transform spectra have been recorded from 15–470 cm^–1 for the far-infrared trosion-rotation band of O-18 methanol in the vibrational ground state. So far, 57 subbands have been assigned in the 15–220 cm^–1 region for a wide range of rotational and torsional states, and their J-independent origins have been determined to an estimated accuracy of ±0.01 cm^–1. The observed origins were found to deviate in many cases by several tenths of a cm^–1 from the values calculated with the previous molecular parameters. Together with 4 known microwave origins, the new data have been fitted to a model torsion-rotation Hamiltonian in order to refine the set ofb-type molecular constants for the ground state. With the new parameter set, the experimental subband origins are reproduced with an rms error of ±0.02 cm^–1, representing a substantial improvement over the earlier situation. The spectroscopic results have also been of great assistance with our assignments of optically-pumped FIR laser emission in CH₃ ¹⁸OH, in providing FIR data for checking the identification of the IR-pump/FIR-laser transition systems through combination loop relations.     

Nonlinear electron-lattice interaction on excited states in polythiophene

In consideration of the effects of the square term of the electron-lattice interaction and the bond-bending term, the energy spectra and the localized vibrational modes around a bipolaron of the polythiophene are investigated based on the one-dimensional and two-dimensional extension SSH model. The results show that, with the influence of the square term, the energy gap increases, the frequencies of all the localized vibrational modes around a bipolaron decrease and their localizations also shift. It is noted that, an even-parity mode has been found which corresponds to absorption peak at 1220 cm⁻¹. When the bond-bending term is considered, the frequencies of the localized modes increase and five new localized modes appear. Among them, one Raman active mode and three infrared active modes may correspond the observed RRS absorption peaks at 1047 cm⁻¹ and three infrared absorption peaks at 370, 1020, 1120 cm⁻¹ in the experiments.     

H2S : First Observation of the (70,0) Local Mode Pair and Updated Global Effective Vibrational Hamiltonian

The absorption spectrum of H₂S has been recorded by intracavity laser absorption spectroscopy in the spectral region 16 180–16 440 cm⁻¹ corresponding to an excitation of the (70^±, 0) local mode pair. Seventy-seven sublevels could be rotationally assigned and fitted with a rms of 0.009 cm⁻¹ by considering the (70^±, 0) local mode pair as isolated. The corresponding vibrational terms combined with all the levels reported in the literature were used to refine the effective vibrational Hamiltonian parameters of H₂³²S. The importance of the Fermi-type interaction is discussed.     

Infrared and Raman spectra of M2Cu2O5 (M=Y,Ho)

We report both Raman and infrared reflectivity spectra of M₂Cu₂O₅ (M=Y, Ho) at room temperature in the spectral range of 30–1000 cm^–1.37 (31) ir and 18 (15) Raman active modes of Y₂Cu₂O₅ (Ho₂Cu₂O₅) are observed. A factor group analysis has been performed to identify the symmetries of the observed modes. Comparing the vibrational spectra of these compounds we conclude that the phonons above 300 cm^–1 originate from the Cu–O vibrations and those under 300 cm^–1 from M–O vibrations.Alexander von Humboldt Foundation fellow     

Local Vibrations of Oxygen-Containing Thermal Donors in Germanium

The vibrational absorption bands associated with some types of double thermal donors (TD) in Ge enriched with the oxygen isotopes ¹⁶O and ¹⁸O have been identified. The thermal donors were formed during heat treatment of Ge:O crystals at 300 and 350°C. Absorption spectra were measured at room temperature and at 10 K. The formation of the thermal donors was accompanied by the appearance of three absorption bands, which in the Ge:¹⁶O spectra at room temperature are located at 600, 740, and 780 cm^–1. In low-temperature measurements, the bands at 600 and 780 cm^–1 exhibited splitting into series of narrow lines (up to 9) associated with some types of thermal donors (TD1–TD9). The absorption spectra measured at 10 K after different cooling conditions display bistability of the first four types of thermal donors (TD1–TD4). In the samples cooled by illumination with light in the region of frequencies of the fundamental absorption of Ge, pairs of lines are observed that belong to the bistable thermal donors in the helium-like configuration of double donors (DD). After cooling the samples in the dark, these pairs of lines are replaced by three new bands, which belong to local vibrational modes of bistable thermal donors in the low-energy neutral configuration. Based on the isotopic shift of the local vibrational modes of the thermal donors in Ge:¹⁶O and Ge:¹⁸O, a rigorous proof of the oxygen atoms entering into the composition of thermal donors is obtained.     

Sum-frequency generation at electrochemical interfaces: Cyanide vibrations on Pt(111) and Pt(110)

We use optical sum-frequency generation to investigate the stretching vibrations of cyanide (CN^–) molecules chemisorbed from aqueous electrolytes on single-crystalline Pt(111)- and Pt(110)-electrode surfaces. For clean and well-ordered Pt(111) electrodes, a single vibrational band between 2080 and 2150 cm^–1 with a nonlinear frequency dependence on the potential is observed and assigned to the CN stretching vibration of chemisorbed cyanide. A second band between 2145 and 2150 cm^–1 with very weak potential dependence appears on a surface which was subjected to oxidation-reduction cycles and is attributed to cyanide associated with a microscopically disordered surface. This assignment is supported by preliminary results for a Pt(110) single-crystal electrode. On a well-ordered (110) surface a single and potential-dependent cyanide vibration between 2070 and 2112 cm^–1 is observed. After oxidation of the cyanide and readsorption, this band is replaced by a higher frequency band at 2144 cm^–1 which is essentially not potential-dependent. Occasionally, additional vibrational bands at lower frequencies not reported in corresponding IR studies are observed on Pt(111).Paper presented at the 129th WE-Heraeus-Seminar on Surface Studies by Nonlinear Laser Spectroscopies, Kassel, Germany, May 30 to June 1, 1994     

Electronic spectrum of cobalt doped rubidium zinc sulphate hexahydrate

Optical absorption spectrum of Co²⁺ doped rubidium zinc sulphate hexahydrate has been investigated both at room and at liquid nitrogen temperatures. The gross features of the observed spectrum are characteristic of octahedral symmetry associated with spin-orbit interaction. The interelectronic repulsion (B, C), crystal field (Dq) and spin-orbit () parameters which give a good fit to the observed band positions areB = 860 cm^–1,C = 3870 cm^–,Dq = 980 cm^–1,= 500 cm^–1. The non-ligand bands observed in the spectrum are attributed to vibrational modes of water molecule.The authors are thankful to the Council of Scientific and Industrial Research, New Delhi (India) for financial support.