scholarly journals XIII. The absorption spectra of the vapours of benzene and its homolognes, at different temperatures and pressures, and of solutions of benzene

1908 ◽  
Vol 208 (427-440) ◽  
pp. 475-528 ◽  
Keyword(s):  
Molecular Weight ◽  
Absorption Spectrum ◽  
Emission Spectrum ◽  
Low Temperatures ◽  
Molecular Absorption ◽  
Absorption Bands ◽  
Royal Dublin Society ◽  
Different Temperatures ◽  
Complete Investigation ◽  
Narrow Bands

The absorption spectrum of benzene in a state of vapour and in solution was photographed by W. A. Miller (‘ Phil. Trans.,’ 1862, vol. 152, II., pp. 861-887). It was also photographed by me in 1880 (‘ J. Chem. Soc.,’ 1881, vol. 39, p. 153; 1882, vol. 41 ; 1885, vol. 47, pp. 685-757), with the instrument and by the method described in the ‘ Scientific Proceedings of the Royal Dublin Society ’ in 1881 (vol. iii., p. 93, New Series) and ‘ J. Society of Arts,’ 1885. For these investigations a molecular weight in milligrammes was employed to test the molecular absorption of the hydrocarbon, but the quantity of vapour was too large even at low temperatures, and the temperature, as since ascertained, was in other experiments too high to admit of the numerous absorption bands being observed, although a series of bands had been photographed from very dilute solutions of benzene in alcohol. The continuous rays which accompany the lines in the emission spectrum of the strongly condensed spark of cadmium were found to afford the best source of light in the region of short wavelengths. J. Pauer, in 1897 (‘ Wiedemann’s Annalen,’ vol. 61, p. 363), also used the cadmium spectrum precisely in the same manner for a more complete investigation of benzene and its homologues, but his experiments were not quantitative, although he compared the same substances in the states of vapour, of liquid, and in solution at a temperature of 20° C. He accurately measured 29 different narrow bands characteristic of the spectrum of the vapour of benzene. More recently this work has been repeated by Wilhelm Friederichs (‘ Zeitschrift f. Wissenschaftl. Photographie,’ 1905, vol. 3, p. 154) and by Leonard Grebe ( loc. cit ., 1905, p . 363).

scholarly journals Ultra-violet transparency of the lower atmosphere, and relative poverty in Ozone

1918 ◽  
Vol 94 (660) ◽  
pp. 260-268 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Solar Spectrum ◽  
Ultra Violet ◽  
Lower Atmosphere ◽  
Atmospheric Ozone ◽  
Absorption Bands ◽  
Relative Poverty ◽  
Narrow Bands

Many years ago it was suggested by Hartley* that the limit of the solar spectrum towards the ultra-violet was attributable to absorption by atmospheric ozone, which, as he showed, would give rise to a general absorption beginning at about the place where the solar spectrum ends. In a recent paper by Prof. A. Fowler and myself,† the evidence for this view was very much strengthened. For it was shown that just on the limits of extinction the solar spectrum shows a series of narrow absorption bands which are eventually merged in the general absorption, and these narrow bands are precisely reproduced in the absorption spectrum of ozone. For my own part, I do not feel any doubt that ozone in the atmosphere is the effective cause limiting the solar spectrum.

Hole-burning kinetics in biomolecules and polymers

1990 ◽  
Vol 68 (9) ◽  
pp. 1023-1026 ◽  
Author(s):  
Takashi Kushida ◽  
Atusi Kurita ◽  
Yasuo Kanematsu ◽  
Yoshikatsu Touyama
Keyword(s):  
Absorption Spectrum ◽  
Ground State ◽  
Low Temperatures ◽  
Laser Light ◽  
Protein A ◽  
Hole Burning ◽  
Absorption Bands ◽  
Broad Distribution ◽  
Doped Polymer ◽  
Electronic Ground

Various characteristics of the change in the absorption spectrum induced by monochromatic laser-light irradiation were compared for a chromophore in a protein, a dye-doped polymer, and a dye-intercalated DNA. It was found that persistent spectral holes are burned in the absorption spectrum of Zn-substituted myoglobin (ZnMb) and of methylene blue intercalated into DNA as easily as of rhodamine 640 in polyvinyl alcohol when the lowest optical absorption bands are illuminated with laser light at low temperatures. In both ZnMb and dye-doped polymer, the hole depth has been found to grow almost logarithmically with burning time. This is explained well by a dispersive burning-kinetics model. A heat-cycle experiment using ZnMb has revealed that the conformational barrier height in the electronic ground state has a broad distribution. We conclude that the hole-burning characteristics are very similar among the systems examined.

Polarimetric Observations of Red Variables: A Study of Gas and Particle Interactions

1979 ◽  
Vol 46 ◽  
pp. 386-408 ◽  
Author(s):  
G. V. Coyne ◽  
I. S. McLean
Keyword(s):  
Wavelength Dependence ◽  
Stellar Atmosphere ◽  
Molecular Absorption ◽  
Absorption Bands ◽  
Absorption And Emission ◽  
Mira Variables ◽  
Stellar Photosphere ◽  
Regular Variable ◽  
Red Supergiants ◽  
Balmer Lines

AbstractIn recent years the wavelength, dependence of the polarization in a number of Mira variables, semi-regular variables and red supergiants has been measured with resolutions between 0.3 and 300 A over the range 3300 to 11000 A. Variations are seen across molecular absorption bands, especially TiO bands, and across atomic absorption and emission lines, especially the Balmer lines. In most cases one can ignore or it is possible to eliminate the effects due to interstellar polarization, so that one can study the polarization mechanisms operating in the stellar atmosphere and environment. The stars Omicron Ceti. (Mira), V CVn (semi-regular variable) and Mu Cephei (M2 la), in addition to other stars similar to them, will be discussed in some detail.Models to explain the observed polarization consider that the continuum flux is polarized either by electron, molecular and/or grain scattering or by temperature variations and/or geometrical asymmetries over the stellar photosphere. This polarized radiation is affected by atomic and molecular absorption and emission processes at various geometric depths in the stellar atmosphere and envelope. High resolution spectropolarimetry promises, therefore, to be a power-rul tool for studying stratification effects in these stars.

scholarly journals A Comparative Electrochemical and Morphological Investigation on the Behavior of NiCr and CoCr Dental Alloys at Various Temperatures

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 256
Author(s):  
Florentina Golgovici ◽  
Mariana Prodana ◽  
Florentina Gina Ionascu ◽  
Ioana Demetrescu
Keyword(s):  
Low Temperatures ◽  
Artificial Saliva ◽  
Electrochemical Stability ◽  
Morphological Investigation ◽  
Dental Alloys ◽  
Ion Release ◽  
Icp Ms ◽  
Different Temperatures ◽  
Good Concordance ◽  
Increasing Temperature

The purpose of our study is to compare the behavior of two reprocessed dental alloys (NiCr and CoCr) at different temperatures considering the idea that food and drinks in the oral cavity create various compositions at different pH levels; the novelty is the investigation of temperature effect on corrosion parameters and ion release of dental alloys. Electrochemical stability was studied together with morphology, elemental composition and ions release determination. The results obtained are in good concordance: electrochemistry studies reveal that the corrosion rate is increasing by increasing the temperature. From SEM coupled with EDS, the oxide film formed on the surface of the alloys is stable at low temperatures and a trend to break after 310K. ICP-MS results evidence that in accordance with increasing temperature, the quantities of ions released from the alloys immersed in artificial saliva also increase, though they still remain small, less than 20 ppm.

The Reactions of Substituted Germyl- and Silylhydrazines with BX3 and CY2 Acceptor Species

1972 ◽  
Vol 50 (4) ◽  
pp. 562-566 ◽  
Author(s):  
L. K. Peterson ◽  
K. I. Thé
Keyword(s):  
Molecular Weight ◽  
Nitrogen Atom ◽  
Low Temperatures ◽  
Adduct Formation ◽  
Steric Effects ◽  
Reaction Products ◽  
Hydrazine Derivatives ◽  
Basic Catalysts ◽  
Series Of Experiments ◽  
Electronic And Steric Effects

Boron trimethyl reacts with each of the organometalloid-hydrazine derivatives Me2NN(R)GeMe3 (R = H, Me, SiMe3) except Me2NN(SiMe3)GeMe3, and with Me2NNHSiMe3, forming 1:1 adducts. With Me2NN(SiMe3)GeMe3 and BMe3, no adduct was formed even at low temperatures. On the basis of p.m.r. spectra, the metalloid-substituted nitrogen atom rather than the terminal nitrogen, is indicated as the basic center at which adduct formation occurs. With BF3, the Si—N and Ge—N bonds of the hydrazine derivatives were cleaved, again indicating attack at the central nitrogen atom. In a series of experiments involving CY2 (Y = O, S) and Me2NN(R)MMe3 (R = H, Me, SiMe3; M = Si, Ge), reaction occurred readily for R = H, but less readily for R = Me and for the compound Me2NN(GeMe3)2, while no reaction was observed for the compounds Me2NN(SiMe3)2 and Me2NN(SiMe3)GeMe3, even when heat or basic catalysts were employed. Reaction products, carbamate and thiocarbamate derivatives, Me2NN(R)C(Y)YMMe3, were characterized on the basis molecular weight, i.r., p.m.r., and mass spectroscopy, and m.p. data. Ease of formation is discussed in terms of electronic and steric effects.

A fluorescence enhancement assay of cell fusion

1977 ◽  
Vol 28 (1) ◽  
pp. 167-177
Author(s):  
P.M. Keller ◽  
S. Person ◽  
W. Snipes
Keyword(s):  
Absorption Spectrum ◽  
Energy Transfer ◽  
Emission Spectrum ◽  
Cell Fusion ◽  
Saturated Hydrocarbon ◽  
Photon Emission ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Hydrocarbon Chains ◽  
Fluorescent Molecules

Two probes were synthesized which consist of fluorescent molecules conjugated to saturated hydrocarbon chains, 18 carbons long, to ensure their localization into cellular membranes. There is an overlap between the emission spectrum of one probe (donor) and the absorption spectrum of the other probe (acceptor). By the use of appropriate wavelengths it is possible to specifically excite the donor probe and record the fluorescence of the acceptor probe. Two cell populations, each labelled with one of the probes, were infected with a virus that causes cell fusion, mixed in equal proportions, and the fluorescence of the acceptor probe measured as a function of time after infection. An increase in fluorescence was observed beginning at the time of onset of cell fusion indicating a mixing of the fluorescent membrane molecules. An investigation of the distance dependence indicated that the increase in fluorescence was mainly due to resonance energy transfer and not to photon emission and reabsorption. Resonance energy transfer requires that the 2 probes be close together and that there be an overlap of the emission spectrum of the donor probe and the absorption spectrum of the acceptor probe. The possible application of this assay to other types of membrane fusion is noted.

SYNTHESIS AND PROPERTIES OF OLIGODIURETANEDIOLS BASED ON A MIXTURE OF (2,4–2,6) TOLUILENDIISOCYANATE

2021 ◽  
Vol 43 (3) ◽  
pp. 198-203
Author(s):  
S.M. KUZMENKO ◽  
◽  
E.O. SPORYAGIN ◽  
O.M. KUZMENKO ◽  
A.YA. PUZENKO ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ir Spectra ◽  
Azeotropic Distillation ◽  
Synthesis Temperature ◽  
Side Reactions ◽  
Absorption Bands ◽  
Formation Reaction ◽  
Viscous Liquids ◽  
Urethane Formation ◽  
Product Control

The paper describes the synthesis, the reaction of a mixture of isomers (2,4–2,6) of toluilendiisocyanate with a double molar excess of aliphatic individual or oligomeric diols, a number of previously unknown oligodiuretanediols and their physicochemical constants. It is shown that with an increase in the synthesis temperature from 50 to 70 °C, the reaction time to complete depletion in the mixture of free NCO-groups decreases from 8–9 hours to 3–4 hours. The reaction temperature of 70–2 °С should be considered optimal, because at higher temperatures side reactions of free NCO-groups with already formed urethane ones are possible. Because the presence of even a small amount of moisture in the diols can provoke side effects during the urethane formation reaction, all of the above diols were dried from the adsorbed moisture by azeotropic distillation with toluene before use in the reaction. Since the final products are even at the synthesis temperature (68–70 °C) viscous liquids, and there are difficulties with the homogenization of the reaction mass during synthesis, and when unloading the finished product from the reaction plant, in all cases, the synthesis was performed in solution cyclohexanone by 50 % by weight of the final product. Control of the reaction was performed by changing the % wt. free NCO-groups in time. The reaction was considered complete if the measured % wt. free NCO-groups in the reaction mixture for at least one hour twice showed zero. The isolated oligodiuretanediols range from solid at room temperature to very viscous products, which significantly depends on the molecular weight of the diol used in the reaction (ie the concentration of urethane groups formed). They are homogeneous, transparent compounds that are readily soluble in esters, ethers, aromatic and halide-containing, aprotic solvents, ketones, poorly or completely insoluble in aliphatic saturated hydrocarbons. The structure of the synthesized oligomeric products is confirmed by functional analysis, IR–spectra. In the IR-spectra of each of the synthesized oligodiuretanediols there are no absorption bands in the region of 2270 cm-1, which confirms the complete completion of the reaction of urethane formation according to the scheme. At the same time, the absorption bands in the region of 3450 cm-1, 1720 cm-1, 1540 cm-1 are fixed, which are characteristic of the presence of urethane groups in the structure of the target products. As the chain length of the diol component –R– increases in the target product (which synchronously leads to an increase in molecular weight), the intensity of these absorption bands decreases, which is associated with a decrease in the concentration of formed urethane groups in the structure of oligodiuretanediols. The refractive index also decreases synchronously. Synthesized series of oligodiuretanediols can be used for synthesis on its basis of other classes of oligomers with the simultaneous presence in the structure of urethane groups. The ability of such compounds to be soluble in solvents of different nature has been studied, which provides information for the directions of their further use (varnishes, enamels, primers).

scholarly journals Synthesis and Optical Performances of a Waterborne Polyurethane-Based Polymeric Dye

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xianhai Hu ◽  
Xingyuan Zhang ◽  
Jin Liu
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Waterborne Polyurethane ◽  
Average Particle ◽  
Particle Sizes ◽  
Hypsochromic Shift ◽  
Absorption Bands ◽  
Polymeric Dye ◽  
Emulsion Particle ◽  
Increasing Temperature

A waterborne polyurethane-based polymeric dye (WPU-CFBB) was synthesized by anchoring 1, 4-bis(methylamino)anthraquinone (CFBB) to waterborne polyurethane chains. The number molecular weight, glass transition temperature, and average emulsion particle size for the polymeric dye were determined, respectively. This polymeric dye exhibited intriguing optical behaviors. The polymeric dye engendered two new absorption bands centered at about 520 nm and 760 nm if compared with CFBB in UV-vis spectra. The 760 nm peak showed hypsochromic shift with the decrease of average particle sizes. The polymeric dye dramatically demonstrated both hypsochromic and bathochromic effects with increasing temperature. The fluorescence intensity of the polymeric dye was much higher than that of CFBB. It was found that the fluorescence intensities would be enhanced from 20°C to 40°C and then decline from 40°C to 90°C. The fluorescence of the polymeric dye emulsion was very stable and was not sensitive to quenchers.

Optical Absorption and Photoluminescence Properties of Dy3+ Ions in Bi2O3-SiO2-B2O3 Glass System

2014 ◽  
Vol 979 ◽  
pp. 280-284
Author(s):  
Narong Sangwaranatee ◽  
Yaowaluk Tariwong ◽  
Sunisa Sarachai ◽  
Jakrapong Kaewkhao ◽  
Natthakridta Chanthima
Keyword(s):  
Optical Absorption ◽  
Emission Spectrum ◽  
Molar Volume ◽  
Borosilicate Glass ◽  
Excitation Wavelength ◽  
Optical Absorption Spectra ◽  
Photoluminescence Spectra ◽  
Photoluminescence Properties ◽  
Melt Quenching ◽  
Absorption Bands

This research studied the effect of dysprosium on the physical, optical and luminescence properties of the bismuth borosilicate glass in compositions 40Bi2O3 : 20SiO2 : (40-x)B2O3 : xDy2O3 (where x = 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mol%). The glass systems have been prepared at 1100 °C by melt quenching technique. The results showed that the density and molar volume of glass samples are between 4.6477 ± 0.0020 to 5.0047 ± 0.0041 g/cm3 and 45.6608 to 48.6797 cm3/mol, respectively. The values of density and molar volume of these glasses were not depend on the Dy2O3 concentration. The optical absorption spectra of glass samples in the UV-Vis-NIR region shows absorption bands at 794, 906, 1094, 1276 and 1690 nm, respectively. The photoluminescence spectra show emission bands at 482 (blue), 576 (green), 663 (yellow) and 756 (red) nm under 453 nm excitation wavelength. The emission spectrum at 576 nm has shown a strongest intensity.

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