Intensity Of OH Band Research Articles

Grafting of cellulose and carboxymethylated cellulose with methyl methacrylate and the dielectric properties of the products

The effect of partial carboxymethylation with various degrees of substitution (DS) on the grafting of cellulose has been studied. The infrared (IR) spectra of these treated wood pulps is investigated. Grafting of wood pulp with methyl methacrylate increases the CO band intensity at 1715–1725 cm −1 while the OH band intensity at 3350 cm −1 decreases as well as carboxymethylation. The crystallinity index (Cr I) is decreased by carboxymethylation but increased by grafting. A new band at 1250 cm −1 is observed in grafted wood pulp which is increased on increasing the graft yield. The dielectric properties of the carboxymethylated samples are affected but decreased by the grafting process. The dielectric properties are decreased by drying at 105°C.

The intensity of amphibole OH bands in the infrared absorption spectrum

Polarized IR spectra of single-crystals of amphiboles show that the molar absorptivity of the fundamental vibrational OH band is strongly wavenumber dependent. The intensity increases by a factor of 1.6 from 3674 cm-1 (tremolite endmember; MgMgMg) to 3618 cm-1 (grunerite endmember; FeFeFe). Spectra obtained from Ca and Fe-Mg amphiboles consist of sharp, well-resolved bands on a well-defined background. The high intensity of the OH bands in Ca and Fe-Mg amphiboles makes it sometimes necessary to thin the samples to under 2 μm thickness, whereas alkali amphiboles can be measured at 25–50 μm thickness.

Effect of isotope dilution on the Fermi resonance in water

AbstractThe additivity of the contributions of HOD, H2O and D2O to the contours of the OH and OD stretching bands was studied in a 1:1 H2O‐D2O mixture. The observed non‐additivity of contours was explained in terms of Fermi resonance changes caused by the variations in resonance intermolecular coupling parameters due to isotope dilution. The integral intensities of OH and OD bands in the mixture were additive.

Infrared Spectroscopic Studies of the Molecular Structure of Grafted Cotton Stalk Pulp

Abstract The infrared spectra of grafted bleached cotton stalks pulp are recorded in the region of 250–4000 cm−1. A new absorption band appearing at 1755 cm−1 is assigned as a carbonyl stretching vibration produced from the graft copolymerization of methylmethacrylate monomer onto cotton stalk pulp. the effect of grafting on the frequency and intensity of OH and carbonyl bands give information about the reaction mechanism of the grafting process.

Excitation modulation by water: effects of desolvation on line intensities, temperatures and ion-atom ratios produced by inductively coupled plasmas

Desolvation of a pneumatically generated aerosol reduces water mass transport by a factor of six but leaves nebuliser efficiency and total mass transport virtually unchanged. A survey of both OH band intensity and the intensity ratios of selected lines leads to the conclusion that aerosol water selectively reduces the intensities of atomic and ionic transitions. Lines with excitation potentials below the dissociation energy of water remain unaffected except when observed very low in the plasma directly above the outer torch tube. Atom and ion lines with energies above the bond energies of water are markedly enhanced by desolvation. Ion-atom intensity ratios, and excitation and ionisation temperatures are also affected by aerosol desolvation.

Spectroscopic Measurements and a New Monitor System of ECR Discharge Cleaning in the Tandem Mirror GAMMA 10

Spectroscopic measurements of a plasma of ECR discharge cleaning in GAMMA 10 device are described. It is shown that the spectrum of OH molecule is observed and that its intensity has a strong correlation with the partial pressure of the M=18 component. A new simple monitor system for OH band intensity has been constructed and shown to be effective.

Aluminium phosphate—zirconia catalysts: I. Structure, texture, acid—base properties and catalytic activity in cyclohexene isomerization of catalysts obtained with propylene oxide

Nitrogen adsorption, X-ray diffraction measurements and infrared spectroscopy were used to study the effects of surface dehydration (773–1273 K) on the textural properties, crystallinity and structure of AlPO 4 ZrO 2 catalysts of different compositions and prepared by precipitation of aluminium orthophosphate (AlPO4) (Al/P= 1) with propylene oxide on commercial monoclinic zirconia (ZrO 2) (Aldrich Chemie, ceramic grade, 99.9 % ). The surface acid—base properties were studied through the irreversible adsorption of organic bases and acids from cyclohexane solutions at 298 K. In addition, the cyclohexene skeletal isomerization (CSI) acid-catalysed test reaction, giving 1- and 3-methylcyclopentenes, was used as a dynamic method for evaluating the number of strong acid sites, the only ones capable of giving rise to skeletal isomerization. Activation energies and selectivities with respect to 1-methylcyclopentene were calculated in terms of the Bassett—Habgood kinetic model for first-order processes in which the surface reaction is the controlling step and the partial pressure of the reactant is low. An increase in ZrO 2 content and/or calcination temperature decreases the surface area and pore volume. This is a consequence of AlPO 4 crystallization to the tridymite form with T d symmetry, in which the phosphorus atoms are surrounded by tetrahedra of oxygen atoms. The decrease in catalytic activity as calcination increases is consistent with not only the decrease in the amount of acid sites measured vs. weaker organic bases but also with the decrease in Brønsted acidity, as shown by the decrease in OH band intensity.

Equatorial mesospheric and F-region airglow emissions observed from latitude 4° south

Simultaneous ground-based measurements of the atmospheric airglow emissions OI 5577, 6300 and 7774 Å, NaD 5893 Å, OH (9, 4) band and O 2 atmospheric (0, 1) band at 8645 Å have been made at an equatorial station, Fortaleza (3.9°S, 38.4°W, geomag. 2.1°S), Brazil, since November 1986. A microprocessor controlled multichannel tilting filter type photometer was constructed for this purpose. Hydroxyl rotational temperatures in the range 190–210 K were obtained from the OH (9, 4) Q and R branch measurements. Surprisingly low OI 5577 Å and NaD intensities, about 40% and 25%, respectively, of those observed at low latitude (23°S), were observed. The OH (9, 4) band intensities, however, did not show any such difference. Time lagged nocturnal intensity variations of the mesospheric emissions observed provide evidence of dynamical effects in the equatorial upper atmosphere.

Polar mesopause gravity wave activity in the sodium and hydroxyl night airglow

The OH (6–2) band and the Na D lines in the night airglow have been observed from Spitsbergen (78°N latitude) during a 3‐day period in the end of November 1983. Regular and quasi‐regular variations in temperature and the OH and sodium intensity were observed and are here interpreted in terms of gravity wave theory. In particular, waves with periods in the range 90–120 min having overlying ripple structure, with periods of 5–15 min, were observed. From the phase difference between the waves in the OH and sodium layer a height difference between the centroid of the two emissions of less than 1 km could be deduced. A gravity wave induced vertical eddy diffusion coefficient in the range 8 × 106 to 8 × 107 cm²/s was estimated from OH‐enhanced intensities. No significant net heating or cooling was observed during gravity wave activity. The gravity wave activity was not associated with geomagnetic activity. Mean OH (6–2) band and sodium night airglow intensities were 1.9 kR and 75 R, respectively.

Raman study of fluorine-doped silica gels

Raman spectroscopy has been used to study the structure of fluorine-doped silica gels as a function of fluorine concentration. Results are reported for gels that were dried at 150°C and gels that were heated at 1000°C. The Raman spectra of the dried gels show that fluorine is present as SiF and various hydrogen-bonded HF groups. Furthermore, the addition of fluorine results in a reduction of the intensity of the Raman bands due to surface silanol groups, and in a change in intensity of the SiO 2 defect lines at 490 and 605 cm −1. After heating the gels at 1000°C, a reduction of the surface SiOH band intensity was observed, but for the F-related Raman bands no change in intensity was found.

Near infrared observations of comet Halley from Vega 2

Spatial distribution of the continuum radiation in the range of 0.95–1.9 μm presumes total dust production rate of the comet of 10 ρ tonne s −1 ( ρ is the dust material density) and its angular distribution proportional cos ϕ. Observations of the water vapor band at 1.38 μ m reveal strong jets, their time shift from the dust jet measured in situ is consistent with gas velocity of 0.82±0.1 km s −1 and dust velocity of 0.55±0.08 km s −1. The OH vibrational-rotational bands observed are excided directly via photolysis of water vapor. Water vapor production rate deduced from the H 2O band and OH band intensities is 8×10 29 s −1. Intensity of the CN(0,0) band result in the CN column density of 9×10 12 cm −2, i.e. larger by a factor of 3 than given by the violet band.

Loss increase in deuterium-doped VAD fibres with heat treatment

The origin of the increase in the intensity of OH bands with heat treatment has been investigated using deuterium-containing VAD fibres. Remarkable loss increases only in the absorption peaks due to the OH ions have been observed after 200?500°C heat treatment applied to three kinds of fibre: drawn from a preform prepared by a D2-O2 flame, and OD-doped in the core and in the cladding. It was confirmed that the origin of the hydrogen causing the loss increase is not in the synthesised glass materials.

Large‐amplitude nightglow OH (8–3) band intensity and rotational temperature variations during a 24‐hour period at 78°N

We report results from a continuous 24‐hour measurement of the OH (8–3) band emission in the nightglow at 78.4°N. A mean temperature of 273 K and a mean band intensity of 596 R were observed. Extreme temperature variations were seen with amplitudes up to ±70 K from the mean. It is suggested that these variations are related to the passage of internal gravity waves. If so, the extreme amplitudes of the variations might imply that the OH emitting layer is situated above 90 km at this latitude in January. The deduced η values (ΔI/I/ΔT/T) favor the ozone mechanism to be responsible for the OH emission with the possibility of an additional mechanism contributing up to 5%.

Deuterium Treatment and Infrared Transmission Spectra of Fused Silica

The effects of deuterium treatment on the in absorption bands infused silica were measured. The deuterium treatment progressively replaces the OH group by the OD group as determined by reduction in the intensity of OH bands. New OD bands of lower intensity were developed at longer wavelengths. The extinction coefficient of the OD group was determined to be 0.57 times lower than that of the OH group.

Spectral line parameters for the X2II- X2II (1,0) bands of OH and ClO for atmospheric applications

Individual spectral line parameters, including line positions, energy levels, and intensities, have been generated for the X 2II- X 2II(1, 0) bands of OH and 35ClO and 37ClO for a temperature of 296 K. At this temperature the OH band intensity is 42.9 cm -1/atm-cm or 1.73 x 10 -18 cm/molecule. For ClO, the band intensity for both isotopes in natural abundance is 11.8 cm -1/atm-cm or 4.76 x 10 -19 cm/molecule. Tables of line parameters for both molecules are available from the authors.

Rotational temperatures and intensities of OH(6-2) and OH(8-3) bands in the night airglow

Clearly resolved spectra of P 1(4), P 2(4), P 1(3), P 2(3), P 1(2) and P 2(2) lines, Q and R branches of the OH(6-2) band in the night airglow have been obtained together with those of P 1(4), P 2(4), P 1(3), P 2(3) and P 1(2) lines of the OH(8-3) band. A tilting-filter photometer which is equipped with a cooled RCA-C31034A photomultiplier and narrow bandpass filters is used. Rotational temperatures are derived from the ratios between P 1 lines, giving an average of 228 ±23 K for the OH(6-2) band and of 231 ± 29 K for the OH(8-3) band for the winter 1977–1978. The correlation between the rotational temperature and intensity is investigated for a time interval of 2 h during the night and for a temperature range of 20 K. It is found that the correlations obtained for intervals between 2000 and 0200 LT are significant and that the correlation calculated from the remainder is insignificant. It is also found that the correlations obtained for the temperature range up to 20 K are not significant. It is shown that the correlation coefficients calculated from the temperature and intensity variations for all the data from the OH (6-2) and (8-3) bands exceed the level of significance, according to Students t-test (5%), which also indicated that the temperature variations during a single night are partially correlated with intensity changes when the spectra are taken every 30 min during the night.

Nightglow OH (8, 3) band intensities and rotational temperature at 23°S

The OH (8, 3) band airglow emission has been observed over 1 year at a latitude of 23°S. The average band intensity observed was 385 Rayleighs with a nocturnal range typically less than 100 R. The nocturnal variation in rotational temperature was usually less than 10°K, and the mean temperature was 179°K. The nocturnal variation of intensity is usually uncorrelated with that of the rotational temperature. Time average values of these parameters do, however, show some correlation. On some occasions large post-twilight and pre-dawn intensity enhancements are observed.

Influence of temperature on the OH-band intensity in the infrared spectra of decationated zeolites X and Y

The IR spectra of several decationated zeolites X and Y were studied in the OH stretching region, and the influence of temperature on the intensity of the bands near 3650 and 3550 cm −1 was investigated. The zeolites were derived from samples initially saturated with Li +, Na +, K +, and Mg 2+ ions, in case of the Y samples and with Na + ions in case of the X samples. Some samples had different contents of residual Na + ions. The exact frequency of the band near 3650 cm −1 was dependent on the amount more than on the nature of the residual cations. The frequency of the OH bands was interpreted in terms of the electrical field in the zeolite cavities. A reversible decrease of the band intensity (20–30%) was observed with increasing temperature below 400 °C together with a small shift to lower frequencies and a broadening of the bands. All these effects are ascribed to the increased thermal motion of the lattice constituents. The ratio of the intensities of the 3550 and 3650 bands was also dependent on the temperature. This was explained by assuming a redistribution of the protons over the different sites. The effect was dependent on the amount of residual ions and the initial value of the band intensity ratio at room temperature.

Hydrogen Bond Systems. Temperature Dependence of OH Frequency Shifts and OH Band Intensities

Hydrogen Bond Systems. Temperature Dependence of OH Frequency Shifts and OH Band Intensities

Nature of the Hydrogen Bond. III. The Measurement of the Infrared Absorption Intensities of Free and Hydrogen-Bonded OH Bands. Theory of the Increase of the Intensity Due to the Hydrogen Bond

The integrated intensities of the infrared OH bands of various compounds have been measured for the free and the hydrogen-bonded states. It is found that the integrated intensity of either the free or the hydrogen-bonded OH band increases as the frequency decreases. It is concluded that the main factor increasing the integrated intensity of the intermolecularly hydrogen-bonded OH bands is the charge transfer through the hydrogen bond. The sign of the change of the dipole moment of the free phenol with the OH distance is discussed. An explanation is given for the weakness of the OH bands of the chelate compounds.