Biljana Minceva-Sukarova

The Raman spectra of ice (Ih, II, III, V, VI and IX) as functions of pressure and temperature

The Raman spectra of various forms of ice Ih, II, III, IX, V and VI of H2O, D2O, H218O and small percentages of HOD in both D2O and H2O have been recorded in their true regions of stability. The high-pressure low-temperature Raman cell used for this work is described. The influence of pressure on the OH and OD stretching modes and the lattice vibrational frequencies is discussed. It is estimated that the pressure compresses the O-O bond lengths on average about 5 pm GPa-1 in the Ih, II, III and V types of ice. An attempt is made to correlate the available spectroscopic and crystallographic data for the various forms of ice in order to make assignments of the Raman- and infrared-active lattice vibrational spectra.

RAMAN SPECTRA OF THIN SOLID FILMS OF SOME METAL SULFIDES

Abstract Thin solid films of metal sulfides: Cu 2 S, CuS, PbS, Sb 2− x Bi x S 3 , Ag 2 S and HgS, and two selenides: Cu 2 Se and PbSe, were prepared by the technique of electroless chemical deposition. For the purpose of recording the Raman spectra, the metal sulfides (selenides) were deposited on glass substrates. All deposited thin films, as well as bulk samples, were characterized by the X-ray diffraction technique. The recorded Raman spectra were compared with the corresponding spectra of bulk metal sulfides (selenides) and discussed in terms of available structural data.

Oriented cadmium oxide thin solid films

A chemical bath deposition technique has been developed for the preparation of Cd(O2)0.88(OH)0.24 thin films on glass and quartz substrates from alkaline media at room temperature. These films were then annealed at 473 K in order to obtain cadmium oxide films. Two baths were used for film preparation. X-Ray diffraction analysis clearly showed that the CdO films obtained from a bath without KBr have a preferred crystalline orientation in the 〈200〉 direction while those obtained from a bath containing KBr had only slightly preferred crystalline orientation in the 〈111〉 direction. The optical bandgap, Eg, was evaluated from the VIS absorption spectra. It was found that Eg for the films oriented in the 〈200〉 direction is 2.63 eV, while it is 2.57 eV for those with the slight 〈111〉orientation. The different values of the cross-over terminal points of absorption and transmittance spectra confirm the difference between the films with different crystalline orientation.

Optical properties of thin solid films of lead sulfide

Abstract The technique of electroless chemical deposition was used for preparation of thin solid films of lead sulfide (PbS). The thin solid PbS films were deposited on a glass substrate previously coated with a very thin layer of Cu 2 S. The optimal temperature of deposition was between 343 and 363 K. The thickness of these films was controlled by changing the concentration of the reaction solutions and the deposition time. The optical properties of these thin solid films of different thickness were determined by means of near infrared spectroscopy, Raman spectroscopy and visible spectroscopy.

Theoretical and experimental (infrared and Raman) study of the host-guest interactions in some Hofmann type clathrates

AbstractThe host–guest interactions in some clathrate-type compounds were studied experimentally and theoretically. Roomtemperature (RT) and low temperature (LT , 100 K) IR, and RT Raman spectra of Hofmann clathrates of the typeM(NH 3 ) 2 M’(CN) 4 ·2C 6 H 6 (where M [ {Ni, Co, Cd, Fe, Mn, Mg, Zn} and M’ [ {Ni, Pd, Pt}) were recorded. The spectraldata show that the positions of almost all bands due to the guest molecule (except those from the g CH modes) remain practicallyunchanged on enclathration. The frequencies of the g CH modes increase with the decrease of the host unit cell volume in a seriesof structurally similar clathrates, and with the decrease of temperature, the first effect being more pronounced. A quantumtheoretical model is proposed to get some insight into the relative importance of particular effects on the spectral behavior of theguest molecule upon enclathration, in which both local electrostatic field and anharmonicity effects are included. The predic-tions of the model are in qualitative agreement with the experimental observations. q1999 Elsevier Science B.V. All rightsreserved.

Vibrational anharmonicity of the C-H out-of-plane vibrations in some Hofmann-type clathrates

Abstract In our previous reports [1,2], we have discussed the host-guest interactions in Hofmann-type clathrates. The motion of the guest (benzene) molecule has been studied through the changes of the frequencies and the shapes of the bands due to CH out-of-plane vibrations. It was found that one of these bands (the one at around 985 cm −1 ), splits at LNT, the splitting being dependent on the volume of the tetragonal unit cell. From the recorded FT-IR and Raman spectra of these clathrates, we have made an attempt to calculate some of the anharmonicity coefficients, X ij , for the C-H out-of-plane bending vibrations in Ni(NH 3 ) 2 Ni(CN) 4 ·2C 6 H 6 and Cd(NH 3 ) 2 Ni(CN) 4 ·2C 6 H 6 Hofmann type clathrates. The interaction of the guest (benzene) molecules in these two lattices has been discussed in terms of the calculated anharmonicity constants and the data were compared with the available data for liquid benzene.

FT-IR Spectroscopic Investigation of Hofmann Td-Type Complexes of 2-, and 3-Chloropyridine

Hofmann-type modified clathrate hosts containing 2- or 3-chloropyridine molecules attached to metal (II) tetracyanocadmate frame, with a given formula: M(Clpy)2Cd(CN)4 where M = Mn, Ni or Cd; Clpy = 2- or 3-chloropyridine, have been synthesised for the first time. Their FT-IR spectra are reported in the 400–4000 cm-1 region. All the vibrational modes of coordinated Clpy are characterised. The spectral features of the compounds studied are found to be similar to each other indicating that they have analogous structures. The coordination effect on the Clpy modes is analyzed.

Micro-Chemical and Spectroscopic Study of Component Materials in 18th and 19th Century Sacred Books

Abstract The Cyrillic books Menology for May (1705), The Bible (1822) and Mirror (1816) were consigned for conservation to the Conservation Laboratory at the National Library in Skopje. The first two books were printed in Moscow, while the third book was issued in Vienna, although it originates from the territory of the former Ottoman Empire, present-day Republic of Macedonia. In order to design a conservation protocol, papers and inks used in the books were characterized and their condition was assessed. Micro-chemical tests were used in order to identify the type of paper fibres and materials added to the paper pulp. FTIR was applied to confirm the findings for the sizing and fillers found in the paper support. Inorganic pigments were analysed by micro-Raman spectroscopy. The original paper in the Russian books was made of rags with less than 5 % lignin content present, whereas the paper in Mirror was made of raw and unbleached hardwood. Distinct types of sizing have been identified: gelatine/alum in Menology for May and Mirror and gelatine/rosin in The Bible. The pigments identified are lamp black, vermilion, Prussian blue and calcite. The study elucidates which internal and external factors could cause further decay of the books and will help in making informed decisions concerning the further preservation of the objects.