The determination of the heat of dissociation of fluorine and of the latent heat of vaporisation of lithium

The heats of dissociation of chlorine, bromine, and iodine have been determined by thermal methods and estimated to be 58·9, 45·2 and 35·2 kilo-cals. respectively. But no data are yet known concerning the heat of dissociation of fluorine. It is very difficult to subject fluorine to the same treatment as Cl 2 , Br 2 and I 2 ( i. e ., heating to a high temperature in a sealed quartz bulb) owing to its extreme chemical reactivity, and hence no direct method of determining the heat of dissociation of fluorine has yet been devised. In the present paper I have determined it indirectly by interpretation of the absorption spectra of alkali fluorides (for the present only NaF and KF). A short theory of the experiment is given below.

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The absorption spectra of the gaseous monoxides of silicon, germanium and tin in the Schumann region

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1954.0165 ◽

1954 ◽

Vol 224 (1158) ◽

pp. 374-388 ◽

Cited By ~ 28

Keyword(s):

Carbon Monoxide ◽

Ionization Potential ◽

Absorption Spectra ◽

Latent Heat ◽

Satisfactory Agreement ◽

Silicon Germanium ◽

Silicon Monoxide ◽

Dissociation Energies

The absorption spectra of the molecules SiO, GeO and SnO have been examined in the region 1250 to 2000Å. A number of new band systems have been found, and vibrational analyses have been carried out. The determination of the dissociation enérgies of these molecules is discussed: the values derived spectroscopically for SiO, GeO and SnO are 185∙ 0 ±6∙ 8 , 155∙ 8 ±5∙ 3 and 126∙ 0 ±4∙ 9 kcal (0° K) respectively. The values for GeO and SnO are in satisfactory agreement with the results of thermochemical work, but the result for SiO suggests that the value of the latent heat of sublimation of silicon is higher than has been suggested, and indicates L si ⋍100 kcal. The correlation between the states of carbon monoxide and of silicon monoxide is briefly considered, and a provisional value for the ionization potential of SiO, 10∙5 1 eV, is derived.

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Experimental Determination of Line Strengths for Selected Carbon Monoxide and Carbon Dioxide Absorption Lines at Temperatures between 295 and 1250 K

Applied Spectroscopy ◽

10.1366/0003702944028074 ◽

1994 ◽

Vol 48 (11) ◽

pp. 1442-1450 ◽

Cited By ~ 4

Author(s):

Patrick J. Medvecz ◽

Kenneth M. Nichols

Keyword(s):

Fourier Transform ◽

High Temperature ◽

Absorption Spectra ◽

High Temperatures ◽

Room Temperature ◽

Theoretical Calculations ◽

Line Strength ◽

Temperature Data ◽

Line Strengths

Fourier transform infrared absorption spectroscopy has been used for the determination of the line strengths of 41 CO and CO2 absorption lines at temperatures between 295 and 1250 K. The CO vibrational-rotational lines were from the P branch of the fundamental absorption band (2150–1950 cm−1) while the CO2 vibrational-rotational lines were from the far wing of the R branch of the v3 fundamental band (2395–2380 cm−1). The intensities of the lines were measured from absorption spectra recorded in a high-temperature gas cell containing known concentrations of CO/CO2/N2 gas mixtures at atmospheric pressure. Absorption spectra were recorded through the cell with the use of a moderate-resolution Fourier transform infrared spectrometer. The absorption spectra were mathematically corrected for distortions resulting from the finite resolution of the spectrometer and for peak overlap. Line strength measurements were made from the corrected peaks by using the Bouguer-Lambert law and assuming a Lorenztian line profile. The experimentally obtained line strengths were evaluated (1) by statistical calculations, (2) by consideration of the validity of the Bouguer-Lambert assumption for these data, (3) by comparison with existing room-temperature and high-temperature data, and (4) by comparison with theoretical calculations. For CO, the statistical analysis suggests that the reported values have an uncertainty of ±10–12%, which is similar to the observed discrepancies with other reported values at room temperature. At high temperatures, the difference between these data and previously reported data and theoretical predictions is less than 10%. For CO2, the statistical uncertainty associated with the line strength calculations is less than 5%, which is also the approximate level of agreement with existing room-temperature data. For lines with m indicies of 65–89, at high temperatures, the values reported in this work agree within 5 to 10% of theoretical calculations.

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Photophysical Detection of Singlet Oxygen

10.5772/intechopen.99902 ◽

2021 ◽

Author(s):

Arnab Maity

Keyword(s):

Singlet Oxygen ◽

Indirect Method ◽

Chemical Reactivity ◽

Direct Method ◽

Therapeutic Process ◽

Fluorescence Emission ◽

Electronically Excited ◽

Detection Probe ◽

Current Research Interest

The chemical reactivity of singlet oxygen (1O2) (SO) derives from its electronically excited state. Being a unique reactive oxygen species SO takes part in many important atmospheric, biological physical, chemical, and therapeutic process and attracted current research interest. To understand the mechanistic pathways in various process the detection and quantification of SO is very important. The direct method of detection is very challenging due to its highly reactive nature. Only direct method of determination of phosphorescence of SO at 1270 nm has been utilised but that also puts some limitation due to very low luminescence quantum yield. Indirect method using UV–Vis spectrophotometric, fluorescent and chemiluminescent probes has been extensively studied for this purpose. Elucidation of various mechanistic processes improvised the use of sophisticated spectroscopic detection probe for SO have been discussed in a simple and lucid manner in this article through citation of literature examples. Four major spectroscopic methods i.e. spectrophotometry, fluorescence, emission and chemiluminescence are elaborately discussed with special emphasis to chemical probes having high selectivity and sensitivity for SO.

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Theoretical Determination of High-Temperature Absorption Spectra for C3 in the Near-UV and VUV

43rd AIAA Thermophysics Conference ◽

10.2514/6.2012-2743 ◽

2012 ◽

Cited By ~ 1

Author(s):

Richard Jaffe ◽

Galina Chaban ◽

David Schwenke

Keyword(s):

High Temperature ◽

Absorption Spectra ◽

Theoretical Determination

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Determination of Carbon Monoxide and Carbon Dioxide Concentrations at Temperatures between 295 and 1250 K Using Fourier Transform Infrared Absorption Spectroscopy

Applied Spectroscopy ◽

10.1366/0003702924123575 ◽

1992 ◽

Vol 46 (12) ◽

pp. 1887-1894 ◽

Cited By ~ 6

Author(s):

Patrick J. Medvecz ◽

Kenneth M. Nichols

Keyword(s):

Fourier Transform ◽

High Temperature ◽

Absorption Band ◽

Absorption Spectra ◽

Absorption Spectroscopy ◽

Infrared Absorption ◽

Infrared Absorption Spectroscopy ◽

Gas Cell ◽

Fundamental Absorption Band

Fourier transform infrared absorption spectroscopy has been used for the determination of CO and CO2 gas concentrations in a high-temperature cell. The gas mixtures analyzed consisted of CO, CO2, and nitrogen; among the samples, the concentration of CO was varied between 0.5 and 4.7% and the CO2 ranged between 0.7 and 4.9%. The temperature of the gas cell was varied between 295 and 1250 K, while the pressure was maintained at atmospheric. Throughout this temperature range, 123 absorption spectra were recorded in the gas cell at a nominal instrument resolution of 0.25 cm−1. The absorption lines used for the concentration analysis consisted of 22 P-branch CO vibrational-rotational lines from the fundamental absorption band, and 19 R-branch CO2 vibrational-rotational lines from the v3 fundamental absorption band. All of the peak heights used for the concentration calculations were first numerically corrected for photometric errors resulting from the finite resolution of the FT-IR instrument. The corrected peak heights were assumed to follow the Bouguer-Lambert law at a constant furnace temperature. Fifty-one of the spectra were used to determine the temperature dependence of the line strength for each of the 41 lines. The experimentally obtained line strengths were then used to determine the gas concentrations of all 123 spectra. The calculated concentrations were compared to NDIR instrument measurements of the gas composition exiting the flow-through high-temperature gas cell. Comparison of the NDIR measured gas concentrations with the calculated concentrations from absorption spectra yielded an average accuracy of 3.6% for the CO spectra and 4.9% for the CO2 spectra.

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