Overtone intensities in neopentane and tetramethylsilane

2001 ◽  
Vol 79 (3) ◽  
pp. 279-290 ◽  
Author(s):  
M WP Petryk ◽  
B R Henry
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Internal Standard ◽  
Vapour Phase ◽  
Absolute Intensity ◽  
Oscillator Strengths ◽  
Local Mode ◽  
Absorbance Spectroscopy ◽  
Vibrational Overtone ◽  
Moment Functions ◽  
Intracavity Laser

The CH vibrational overtone transitions of vapour phase neopentane-d0, -d6, -d9, and tetramethylsilane (TMS) are investigated via conventional absorbance spectroscopy and intracavity laser photoacoustic spectroscopy (ICL-PAS). The CH stretching overtones of neopentane-d0 are observed in the energy range Δ VCH = 3–9 (8 400 to 22 000 cm–1) and in the range Δ VCH = 3–8 for the remaining neopentanes and TMS. While we have extended the range of previous studies, our main focus in this work has been on overtone intensities. The oscillator strengths of the neopentane-d0 overtone transitions are determined directly by conventional absorbance spectroscopy for Δ VCH = 3–6 and via ICL-PAS with methane as an internal standard for Δ VCH = 4–7. The correspondence of measured intensities for the two techniques demonstrates the usefulness of the latter for higher overtone ICL-PAS spectra. The experimentally determined Morse parameters ω˜ and ω˜x as well as the harmonically coupled anharmonic oscillator (HCAO) model are used in conjunction with dipole moment functions that are derived from ab initio computations to calculate overtone transition intensities for the neopentanes and TMS. Key words: local mode, overtone transition, absolute intensity, photoacoustic spectroscopy.

Local mode mixing of the vibrational overtone manifold of the CH stretching modes in toluene

1988 ◽  
Vol 148 (4) ◽  
pp. 337-342 ◽  
Author(s):  
Pradip N. Ghosh ◽  
Prabhat K. Panja ◽  
Chandra M. Pal
Keyword(s):  
Local Mode ◽  
Vibrational Overtone ◽  
Mode Mixing

Article

1999 ◽  
Vol 77 (11) ◽  
pp. 1775-1781 ◽  
Author(s):  
Christopher D Daub ◽  
Bryan R Henry ◽  
Martin L Sage ◽  
Henrik G Kjaergaard
Keyword(s):  
Dipole Moment ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Correlation ◽  
Moment Function ◽  
Polynomial Method ◽  
Small Contribution ◽  
Least Squares Regression ◽  
Vibrational Overtone ◽  
Moment Functions

Two studies of aspects of modelling dipole moment functions of XH bonds in small molecules for use in calculating overtone intensities have been undertaken. The first study deals with the fitting of ab initio calculations of the dipole moment at discrete points to a functional form. The two methods that are compared are the use of least-squares regression and the use of interpolating polynomials. The interpolating polynomial method is deemed superior due to its greater efficiency in terms of the number of points necessary to obtain reasonable results. The second study attempts to explain the indifference of calculated overtone intensities to the inclusion of electron correlation in the ab initio calculation of the dipole moment function. It is found that in most cases the influence of electron correlation can be modelled as a function with a very small matrix element, which results in a very small contribution to the overtone intensity.Key words: dipole moment function, vibrational overtone intensities, electron correlation, ab initio calculations.

A theoretical study of the B′2Σ+–X2Σ+ band system in MgH and MgD

1979 ◽  
Vol 57 (8) ◽  
pp. 1178-1184 ◽  
Author(s):  
M. L. Sink ◽  
A. D. Bandrauk
Keyword(s):  
Dipole Moment ◽  
Theoretical Study ◽  
Transition Probabilities ◽  
Band System ◽  
Dipole Moments ◽  
Electronic States ◽  
Oscillator Strengths ◽  
Moment Functions ◽  
Condon Factors ◽  
Franck Condon

Ab initio Cl calculations of the transition moment for the B′2Σ+–X2Σ+ transition in MgH are reported. Theoretical values for the Franck–Condon factors, band strengths, band oscillator strengths, and transition probabilities have been computed for MgH and MgD. An analysis of our results for this system predicts many bands to be observable which have not yet been identified. Dipole moment functions and vibrationally averaged dipole moments are given for the X2Σ+, A2Π, and B′2Σ+ electronic states.

Vibrational overtone study of five-membered aromatic heterocycles: local mode interpretations

1991 ◽  
Vol 95 (20) ◽  
pp. 7659-7664 ◽  
Author(s):  
Michael G. Sowa ◽  
Bryan R. Henry ◽  
Yoshihiro Mizugai
Keyword(s):  
Local Mode ◽  
Aromatic Heterocycles ◽  
Vibrational Overtone

ChemInform Abstract: LOCAL MODE OSCILLATOR STRENGTHS IN BENZENE

1979 ◽  
Vol 10 (16) ◽  
Author(s):  
M. S. BURBERRY ◽  
A. C. ALBRECHT
Keyword(s):  
Oscillator Strengths ◽  
Local Mode

ANALYSIS OF GEOLOGICAL MATERIALS BY ICP-AES WITH CALIBRATION IN CONCENTRATION RATIO

2019 ◽  
Vol 85 (6) ◽  
pp. 24-29
Author(s):  
T. A. Karimova ◽  
G. L. Buchbinder
Keyword(s):  
Inductively Coupled Plasma ◽  
Concentration Ratio ◽  
Total Error ◽  
Internal Standard ◽  
Atomic Emission ◽  
Absolute Intensity ◽  
Emission Spectrometry ◽  
Calibration Error ◽  
Intermediate Precision ◽  
Geological Materials

A method of calibration in relative concentrations (concentration ratio) previously used only in analysis of non-ferrous and ferrous metals was first implemented when performing silicate analysis of geological materials using atomic emission spectrometry with inductively coupled plasma (AES-ICP). Prior to apply the Concentration Calibration Ratio to analysis of geological materials it is necessary to consider and address the following problems: some of the components are not determined by ICP-AES, matrix elements may be present in different oxidation states. Sample preparation of ores and geological materials was carried out in autoclaves heated at 180°C using HotBlock 200 system. A mixture HCl/HNO3/HF was used at the first step and then added with a 4% H3BO3 solution. The repeatability and intermediate precision of determination when using Concentration Ratio Calibration, calibration without internal standard and Calibration with In as internal standard are compared for determination of SiO2 (content 40 – 75%), Al2O3 (5 – 20%), CaO (0.25 – 15%), MgO (0.1 – 15%), Fe2O3 (0.5 – 15%), Na2O (0.5 – 10%), K2O (0.5 – 5%), P2O5 (0.01 – 0.3%), MnO (0.03 – 0.5%), and TiO2 (0.05 – 2%). The use of Concentration Ratio Calibration provides better metrological characteristics, repeatability and precision in analysis of geological materials compared to other calibration procedures due to elimination of the calibration error of balances and volumetric flasks from total error of analysis; measuring the large intensities of the base element; and better accuracy of measuring the intensity ratio compared to absolute intensity measurements.

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