The Temperature Dependence of Band Maxima Molar Absorptivities of the Carbon-Bromine Stretching Modes in n-Butyl Bromide in the Liquid Phase

1987 ◽  
Vol 41 (5) ◽  
pp. 807-809 ◽  
Author(s):  
J. E. Katon ◽  
Stanislaus R. Lobo ◽  
J. C. Simpson
Keyword(s):  
Mathematical Model ◽  
Infrared Spectroscopy ◽  
Liquid Phase ◽  
Temperature Dependence ◽  
Energy Difference ◽  
Temperature Dependent ◽  
Butyl Bromide ◽  
Absorption Bands ◽  
A Value

In the determination of energy differences of conformers in the fluid states by infrared spectroscopy it is nearly always assumed that the ratio of the molar absorptivities at the band maxima of two separate absorption bands is independent of temperature. This assumption has been tested by fitting the data obtained from n-butyl bromide to a mathematical model which can be iterated to convergence on a value of the energy difference between the trans and gauche isomers. The data utilized are the C-Br stretching modes of the two conformers at about 655 and 567 cm−1, respectively. It is shown that the assumption of temperature independence of the ratios of the molar absorptivities at the peak maxima is a good one, although both values are individually temperature dependent.

scholarly journals Temperature Dependence of G and D’ Phonons in Monolayer to Few-Layer Graphene with Vacancies

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Mingming Yang ◽  
Longlong Wang ◽  
Xiaofen Qiao ◽  
Yi Liu ◽  
Yufan Liu ◽  
...  
Keyword(s):  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Intrinsic Properties ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Layer Graphene ◽  
A Value ◽  
Few Layer Graphene

Abstract The defects into the hexagonal network of a sp2-hybridized carbon atom have been demonstrated to have a significant influence on intrinsic properties of graphene systems. In this paper, we presented a study of temperature-dependent Raman spectra of G peak and D’ band at low temperatures from 78 to 318 K in defective monolayer to few-layer graphene induced by ion C+ bombardment under the determination of vacancy uniformity. Defects lead to the increase of the negative temperature coefficient of G peak, with a value almost identical to that of D’ band. However, the variation of frequency and linewidth of G peak with layer number is contrary to D’ band. It derives from the related electron-phonon interaction in G and D’ phonon in the disorder-induced Raman scattering process. Our results are helpful to understand the mechanism of temperature-dependent phonons in graphene-based materials and provide valuable information on thermal properties of defects for the application of graphene-based devices.

Spectroscopic and electrical studies of all- trans β-carotene crystals

1967 ◽  
Vol 301 (1465) ◽  
pp. 173-193 ◽  
Keyword(s):  
Electronic Absorption Spectra ◽  
Dark Conductivity ◽  
Electrical Measurements ◽  
Absorption Bands ◽  
A Value ◽  
Polarization Behaviour ◽  
Current Characteristics ◽  
Β Carotene ◽  
Weak Peak

Single crystals of all- trans β -carotene have been grown and spectroscopic, optical and electrical properties measured. Electronic absorption spectra have been measured at liquid nitrogen and room temperature, and the polarization of the absorption bands in the mono-clinic form determined. The polarization behaviour is briefly discussed. The electrical measurements include a determination of the dark conductivity, giving a value for the electrical activation energy of 1·45 eV. Some crystals were observed to give unusual voltage current characteristics and to give rise to current pulses at a steady applied voltage. Photoconductivity measurements show a weak peak at 25000 cm -1 in the region where maximum light absorption occurs, and a much stronger peak at 13300 cm -1 . The various processes which could be responsible for this and for the origin of the latter peak are discussed.

scholarly journals Temperature-Dependent Broadening of the Ultraviolet Photoelectron Spectrum of Au(110)

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5969
Author(s):  
Tomonari Nishida ◽  
Ikuo Kinoshita ◽  
Juntaro Ishii
Keyword(s):  
Fourier Transform ◽  
Temperature Dependence ◽  
Photoelectron Spectroscopy ◽  
Photoelectron Spectrum ◽  
Thermodynamic Temperature ◽  
Temperature Dependent ◽  
Photoelectron Emission ◽  
The Fourier Transform ◽  
The Relationship

To determine the thermodynamic temperature of a solid surface from the electron energy distribution measured by photoelectron spectroscopy, it is necessary to accurately evaluate the energy broadening of the photoelectron spectrum and investigate its temperature dependence. Broadening functions in the photoelectron spectrum of Au(110)’s surface near the Fermi level were estimated successfully using the relationship between the Fourier transform and the convolution integral. The Fourier transform could simultaneously reduce the noise of the spectrum when the broadening function was derived. The derived function was in the form of a Gaussian, whose width depended on the thermodynamic temperature of the sample and became broader at higher temperatures. The results contribute to improve accuracy of the determination of thermodynamic temperature from the photoelectron spectrum and provide useful information on the temperature dependence of electron scattering in photoelectron emission processes.

Low-Temperature Mobility of Thionine in a Faujasite Cage

1994 ◽  
Vol 366 ◽  
Author(s):  
F. W. Deeg ◽  
M. Ehrl ◽  
C. Bräuchle
Keyword(s):  
Low Temperature ◽  
Pore Structure ◽  
Zeolite Y ◽  
Three Dimensional ◽  
Molecular Size ◽  
Energy Difference ◽  
Temperature Dependent ◽  
Host Interaction ◽  
The Relationship

ABSTRACTWe have used low-temperature optical spectroscopy to characterize the guest/host interaction of thiazine and oxazine dyes encapsulated in the three-dimensional pore structure of faujasite cages. The system thionine in dehydrated zeolite-Y exhibits a thermal and optical equilibrium between two spectroscopically distinguishable species. Temperature-dependent measurements allow the determination of the energy difference and barrier between these two forms as 170 cm−1 and 120 cm−1, respectively. The two forms are associated with two different locations/conformations of the chromophore within the faujasite pore structure. The degree of freedom responsible for the interconversion of the two forms is extremely sensitive to the relationship between molecular size and form of the void.

The Temperature Dependence of Band Maxima Molar Absorptivities of the Carbon-Halogen Stretching Mode in Tertiary Butyl Chloride, Bromide, and Iodide in the Liquid Phase

1987 ◽  
Vol 41 (3) ◽  
pp. 468-471 ◽  
Author(s):  
J. E. Katon ◽  
Stanislaus R. Lobo ◽  
J. C. Simpson
Keyword(s):  
Mathematical Model ◽  
Liquid Phase ◽  
Temperature Dependence ◽  
Linear Relationship ◽  
Molar Absorptivity ◽  
Absolute Temperature ◽  
Significant Error ◽  
Butyl Chloride ◽  
Tertiary Butyl ◽  
Relationship Of

The absorbances at the peak maxima of the carbon-halogen stretching mode of t-butyl chloride, bromide, and iodide have been measured as a function of temperature. With the use of corrected concentration and pathlengths, these data have been converted into molar absorptivities at the respective peak maxima. The data have then been analyzed statistically for the purpose of developing a mathematical model for the dependency of molar absorptivity, at these peak maxima, on the absolute temperature. In all three cases, a linear relationship of the form e = XT + Y was found to satisfactorily fit the data. The molar absorptivity of all three band maxima decreases approximately 1% per Kelvin. This result indicates that attempts to apply Beer's law at temperatures other than that used to derive the constants will lead to significant error if the temperatures differ by more than a few degrees.

Infrared Spectra of Cured and Uncured Rubbers

1959 ◽  
Vol 32 (2) ◽  
pp. 628-638
Author(s):  
G. A. Blokh ◽  
A. F. Mal'nev
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared ◽  
Infrared Absorption Spectrum ◽  
Infrared Region ◽  
Absorption Bands ◽  
Linear Absorption ◽  
Infrared Rays ◽  
Other Substances ◽  
The Individual

Abstract The newest physical-chemical methods of research enlarge the scope of study of the vulcanization process. There is a possibility of studying the structure changes during vulcanization of rubber by the application of infrared spectroscopy. Infrared rays are selectively absorbed. Therefore the infrared absorption spectrum can be used as a characteristic property of a substance and could be used for analytical purposes. The large spectral range of the infrared rays indicates their importance for the study of the properties and structure of substances; this makes possible the determination of the moments of inertia of atomic nuclei and molecules, isotopic mass, arrangement and strength of atomic bonds in the molecule and the frequencies of their vibrations. By knowing the frequencies for pure substances, molecular analyses of complicated mixtures of various organic rubbers, accelerators and other substances could be performed. The study of linear absorption spectra is the basis of the spectrographic method in the infrared region. Since the frequencies of near infrared radiation correspond to the characteristic frequencies of the atoms in the molecules, this method could be used to obtain interesting information concerning the structure of organic molecules, the chemical structure of high molecular weight compounds, the determination of the presence of specific groups or atoms in the rubber molecule, the character of the bonds between these groups and the order of arrangement of the individual chain links. This is true because the position of the absorption bands, which are specific for a given group of atoms, is practically the same for the different combinations in which the group occurs. The complicated process of polymerization of diene and vinyl compounds and the structure of different types of rubbers can be investigated with the aid of infrared spectroscopy. For example, Table I lists the characteristic absorption frequencies in the infrared region for some important chemical combinations.

Bestimmung der Röntgen-Debye-Temperatur aus dem Borrmann-Effekt in Germanium / Determination of the X-ray Debye Temperature in Germanium by Means of the Borrmann Effect

1973 ◽  
Vol 28 (7) ◽  
pp. 1204-1213 ◽  
Author(s):  
J. Ludewig
Keyword(s):  
Temperature Dependence ◽  
Compton Scattering ◽  
Debye Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Perfect Crystal ◽  
Photoelectric Absorption ◽  
Temperature Dependent ◽  
X Ray

The anomal transmission of CuK radiation through "thick"' perfect crystal slices of Germanium is strongly temperature dependent. This temperature dependence was measured between 293 and 6 K in the (220) symmetric Laue case and used to evaluate the Debye temperature θM . The wellknown uncorrected value θ′M = 290K was obtained near room temperature. Taking into account TDS and Compton scattering in addition to the photoelectric absorption the corrected value θM = 294 or 296 K was found, depending on the source of data. With decreasing temperature the corrected θM increases slightly up to a maximum at very low temperatures, as predicted by Batterman and Chipman and by Salter.

scholarly journals Interpretation of Frenkel’s theory of sintering considering evolution of activated pores: III. Determination of equilibrium sintering time

2015 ◽  
Vol 47 (2) ◽  
pp. 215-219
Author(s):  
C.L. Yu ◽  
D.P. Gao ◽  
F. Wang ◽  
R.J. Huo ◽  
X.M. Hao ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Liquid Phase ◽  
Liquid Phase Sintering ◽  
Experimental Results ◽  
Equilibrium Time ◽  
Sintering Time ◽  
Good Accordance ◽  
Cordierite Glass ◽  
The Mathematical Model

In this article, the Frenkel?s theory of liquid-phase sintering was interpreted regarding pores as the activated volume. The mathematical model established by Nikolic et al. was used to infer the equilibrium sintering time at varied sintering temperatures during the isothermal sintering of codierite glass by Giess et al. Through the calculation, the equilibrium time at 800?C, 820?C, 840?C and 860?C is inferred to be 7014.42mins, 1569.65mins, 368.92mins and 114.61mins, respectively. The equilibrium time decreases as the temperature increases. And the theoretical value is in good accordance with the experimental results. Thus, the model established by Nikolic et al. can be applied successfully to predict the equilibrium sintering time of the cordierite glass at varied temperatures during isothermal sintering.

scholarly journals Experimental determination of the temperature dependence of oxygen-isotope fractionation between water and chitinous head capsules of chironomid larvae

2021 ◽  
Author(s):  
Alex Lombino ◽  
Tim Atkinson ◽  
Stephen J. Brooks ◽  
Darren R. Gröcke ◽  
Jonathan Holmes ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Oxygen Isotope ◽  
Oxygen Isotopes ◽  
Isotope Fractionation ◽  
Temperature Dependent ◽  
Oxygen Isotope Fractionation ◽  
Chironomid Larvae ◽  
Increasing Temperature ◽  
The Relationship

AbstractOxygen-isotope values of invertebrate cuticle preserved in lake sediments have been used in palaeoenvironmental reconstructions, generally with the assumption that fractionation of oxygen isotopes between cuticle and water ($$\upalpha_{\text{cuticle}-\text{H}_{2}\text{O}}$$ α cuticle - H 2 O ) is independent of temperature. We cultured chironomid larvae in the laboratory with labelled oxygen-isotope water and across a range of closely controlled temperatures from 5 to 25 °C in order to test the hypothesis that fractionation of oxygen isotopes between chironomid head capsules and water ($$\upalpha_{\text{chironomid}-\text{H}_{2}\text{O}}$$ α chironomid - H 2 O ) is independent of temperature. Results indicate that the hypothesis can be rejected, and that $$\upalpha_{\text{chironomid}-\text{H}_{2}\text{O}}$$ α chironomid - H 2 O decreases with increasing temperature. The scatter in the data suggests that further experiments are needed to verify the relationship. However, these results indicate that temperature-dependence of $$\upalpha_{\text{chironomid}-\text{H}_{2}\text{O}}$$ α chironomid - H 2 O should be considered when chironomid δ18O is used as a paleoenvironmental proxy, especially in cases where data from chironomids are combined with oxygen-isotope values from other materials for which fractionation is temperature dependent, such as calcite, in order to derive reconstructions of past water temperature.

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