THE RAMAN SPECTRUM OF ETHANE-d6

1962 ◽  
Vol 40 (11) ◽  
pp. 1567-1582 ◽  
Author(s):  
D. W. Lepard ◽  
D. M. C. Sweeney ◽  
H. L. Welsh
Keyword(s):  
Raman Spectrum ◽  
Spectral Resolution

The Raman spectrum of C2D6 at 1 atm pressure was photographed with a spectral resolution of ~ 0.4 cm−1. Of the six Raman-active fundamentals, v1, v2, v3, v10, and v11 were observed, and the rotational structures of v2, v3, and v10 were analyzed. The structure of v10 confirms the D3d model for the molecule and the analysis gave A0 = 1.3416 cm−1. This value, along with recent infrared values of B0 for C2H6 and C2D6, gives r0(C—H) ≡ r0(C—D) = 1.0914 ± 0.0003 Å, r0(C—C) = 1.5362 ± 0.0005 Å, and [Formula: see text].

scholarly journals Spatial Heterodyne Raman Spectrometer (SHRS) for In Situ Chemical Sensing Using Sapphire and Silica Optical Fiber Raman Probes

2019 ◽  
Vol 73 (10) ◽  
pp. 1160-1171 ◽  
Author(s):  
Joshua M. Ottaway ◽  
Ashley Allen ◽  
Abigail Waldron ◽  
Phillip H. Paul ◽  
S. Michael Angel ◽  
...  
Keyword(s):  
Raman Spectrum ◽  
Spectral Resolution ◽  
Laser Excitation ◽  
Broad Band ◽  
Silica Fiber ◽  
Array Detector ◽  
Fiber Probe ◽  
Raman Spectrometer ◽  
Raman Probe ◽  
Sapphire Fiber

A spatial heterodyne Raman spectrometer (SHRS), constructed using a modular optical cage and lens tube system, is described for use with a commercial silica and a custom single-crystal (SC) sapphire fiber Raman probe. The utility of these fiber-coupled SHRS chemical sensors is demonstrated using 532 nm laser excitation for acquiring Raman measurements of solid (sulfur) and liquid (cyclohexane) Raman standards as well as real-world, plastic-bonded explosives (PBX) comprising 1,3,5- triamino- 2,4,6- trinitrobenzene (TATB) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) energetic materials. The SHRS is a fixed grating-based dispersive interferometer equipped with an array detector. Each Raman spectrum was extracted from its corresponding fringe image (i.e., interferogram) using a Fourier transform method. Raman measurements were acquired with the SHRS Littrow wavelength set at the laser excitation wavelength over a spectral range of ∼1750 cm−1 with a spectral resolution of ∼8 cm−1 for sapphire and ∼10 cm−1 for silica fiber probes. The large aperture of the SHRS allows much larger fiber diameters to be used without degrading spectral resolution as demonstrated with the larger sapphire collection fiber diameter (330 μm) compared to the silica fiber (100 μm). Unlike the dual silica fiber Raman probe, the dual sapphire fiber Raman probe did not include filtering at the fiber probe tip nearest the sample. Even so, SC sapphire fiber probe measurements produced less background than silica fibers allowing Raman measurements as close as ∼85 cm−1 to the excitation laser. Despite the short lengths of sapphire fiber used to construct the sapphire probe, well-defined, sharp sapphire Raman bands at 420, 580, and 750 cm−1 were observed in the SHRS spectra of cyclohexane and the highly fluorescent HMX-based PBX. SHRS measurements of the latter produced low background interference in the extracted Raman spectrum because the broad band fluorescence (i.e., a direct current, or DC, component) does not contribute to the interferogram intensity (i.e., the alternating current, or AC, component). SHRS spectral resolution, throughput, and signal-to-noise ratio are also discussed along with the merits of using sapphire Raman bands as internal performance references and as internal wavelength calibration standards in Raman measurements.

THE RAMAN SPECTRUM OF ETHANE-1,1,1-d3

1967 ◽  
Vol 45 (12) ◽  
pp. 3823-3835 ◽  
Author(s):  
D. E. Shaw ◽  
H. L. Welsh
Keyword(s):  
Raman Spectrum ◽  
Spectral Resolution ◽  
Rotational Structure ◽  
Rotational Constants

The Raman spectrum of CH3–CD3 at 1 atm pressure was photographed with a spectral resolution of ~0.3 cm−1. The nondegenerate ν1 and ν3 and the doubly degenerate ν7 and ν11 fundamentals were observed. Analyses of the rotational structure of the ν3 and ν7 bands gave the rotational constants, B0 = 0.549 1 ± 0.000 3 cm−1 and A0 = 1.7809 ± 0.0016 cm−1, respectively. These are consistent with rotational constants previously obtained for C2H6 and C2D6.

THE RAMAN SPECTRUM OF METHANE

1960 ◽  
Vol 38 (10) ◽  
pp. 1291-1303 ◽  
Author(s):  
M. A. Thomas ◽  
H. L. Welsh
Keyword(s):  
Raman Spectrum ◽  
Spectral Resolution

The Raman spectrum of CH4 was obtained with a spectral resolution of ~0.3 cm−1, and rotational analyses of the ν and ν2 bands were carried out. The B0 values obtained from the ν2 and ν3 bands are 5.240 ± 0.002 and 5.2406 ± 0.0011 cm−1, respectively; the value of ν0 determined from the latter is 1.09403 ± 0.00016 Å. The rotational levels of the ν = 1 state of ν2 are double with B1 values of 5.313 and 5.379 cm−1. The rotational levels of the ν = 1 state of ν2 do not follow the theoretical formulae exactly; the deviations for the 13 branches observed can be expressed by using three different B1 values, 5.178, 5.195, and 5.212 cm−1. The value of ζ3 is 0.054. The band origins are: ν1 = 2916.7, ν2 = 1533.6, and ν3 = 3018.9 cm−1.

Electronic Raman effect of nitric oxide at high resolution

1969 ◽  
Vol 47 (24) ◽  
pp. 2879-2881 ◽  
Author(s):  
H. Fast ◽  
H. L. Welsh ◽  
D. W. Lepard
Keyword(s):  
Nitric Oxide ◽  
Raman Spectrum ◽  
High Resolution ◽  
Spectral Resolution ◽  
Intensity Distribution ◽  
Electronic Transition ◽  
Raman Effect ◽  
Rotational Structure ◽  
Transition Formula

The rotational Raman spectrum of gaseous NO was photographed with a spectral resolution of ~0.3 cm−1. In longer exposures the rotational structure of the electronic transition, [Formula: see text], was also observed. It consists of O, P, Q, R, and S branches and has an intensity distribution in accordance with theory.

THE RAMAN SPECTRUM OF ETHANE

1955 ◽  
Vol 33 (10) ◽  
pp. 588-599 ◽  
Author(s):  
J. Romanko ◽  
T. Feldman ◽  
H. L. Welsh
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Spectral Resolution ◽  
Raman Band ◽  
Point Group ◽  
Infrared Band ◽  
Torsional Frequency

The rotational and rotation-vibrational Raman spectra of gaseous ethane at 1–3 atm. pressure have been photographed with a spectral resolution of approximately 1 cm.−1. Analyses of the rotational structures of the ν1 and ν2 totally symmetric bands were carried out; only the Q branch of the ν2 band was observed. The structures of the degenerate ν10 and ν11 bands were analyzed; however, no trace of ν12 was found. The structure of the ν10 band shows beyond doubt that the point group of the molecule is D3d. From the ν11+ν4 infrared band, and the ν11 Raman band, the value, 278.4 cm.−1, is deduced for the torsional frequency ν4.

scholarly journals Optimizing the Raman signal for characterizing organic samples: The effect of slit aperture and exposure time

2009 ◽  
Vol 23 (2) ◽  
pp. 71-80 ◽  
Author(s):  
João Carlos Lázaro ◽  
Marcos Tadeu T. Pacheco ◽  
Kátia Calligaris Rodrigues ◽  
Carlos José de Lima ◽  
Leonardo Marmo Moreira ◽  
...  
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Exposure Time ◽  
Spectral Resolution ◽  
Spectral Intensity ◽  
Band Width ◽  
Infrared Light ◽  
Raman Signal ◽  
Specific Chemical ◽  
Time Exposure

The present work is focused on the influence of the slit aperture and time exposure of the infrared light on the Charge Coupled Device (CCD) in relation to their physical effects, in order to improve the Raman spectrum characteristics. Indeed, the alterations in slit aperture and CCD time exposure affect significantly important spectral properties, such as the spectral intensity, Signal to Noise Ratio (SNR) and band width resolution of the Raman spectra. Therefore, the present proposal has the aim of to found the optimum conditions of instrumental arrangement, involving the minimum collection time and maximum signal quality in dispersive Raman spectrometers. Samples of dehydrated human teeth and naphthalene were evaluated with a Raman dispersive spectrometer employing excitation wavelength of 830 nm in several integration times and spectrometer slit apertures. The analysis of the spectral intensity, SNR and band width of selected Raman peaks allowed to infer that these properties of a dispersive Raman spectrum depend directly of the exposure time on the detector as well as spectrograph slit aperture. It is important to register that the higher SNR was obtained with higher exposure time intervals. To the samples evaluated in the present article, the band width has lower values for slit apertures of 100–150 μm, i.e., in this aperture range the spectral resolution is maximum. On the publisher-id hand, the intensity and SNR of the Raman spectra becomes optimal for slit apertures of 150–200 μm, since this aperture does not affect significantly the integrity of the Raman signal. In this way, we can to propose that in approximately 150 μm, it is possible to obtain an optimum condition, involving spectral resolution as well as SNR and spectral intensity. In any case, depending of the priorities of each spectral measurement, the instrumental conditions can be altered according with the necessities of each specific chemical analysis involving a determined sample. The present data are discussed in details in agreement with recent data from literature.

THE RAMAN SPECTRUM OF METHANE-d4

1961 ◽  
Vol 39 (3) ◽  
pp. 419-436 ◽  
Author(s):  
R. A. Olafson ◽  
M. A. Thomas ◽  
H. L. Welsh
Keyword(s):  
Raman Spectrum ◽  
Spectral Resolution

The Raman spectrum of CD4 at 1 atm pressure was photographed with a spectral resolution of ~0.4 cm−1, and rotational analyses of the ν2 and ν3 bands were carried out. The B0 values obtained from the ν2 and ν3 bands are 2.6330 ± 0.0007 and 2.6328 ± 0.0007 cm−1, respectively; the value of r0 determined from the former is 1.09181 ± 0.00029 Å. The rotational levels of the ν = 1 state of ν2 are split with effective B1 values equal to 2.6894, 2.7351, and 2.7434 cm−1. Thirteen of the fifteen branches of the ν3 band were observed; these also show multiple B1 values. The value obtained for ζ3 is 0.1648. Structure was observed but not analyzed in the ν1, 2ν4, and ν2 + ν4 bands. On the basis of the Raman data the structures of the ν2 and ν3 infrared bands are discussed.

Axial Observation of X-Ray Spectra from a Beam-Foil Source

1988 ◽  
Vol 102 ◽  
pp. 339-342
Author(s):  
J.M. Laming ◽  
J.D. Silver ◽  
R. Barnsley ◽  
J. Dunn ◽  
K.D. Evans ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Heavy Ion ◽  
Ion Beams ◽  
Beam Axis ◽  
Doppler Broadening ◽  
X Ray ◽  
Beam Foil

AbstractNew observations of x-ray spectra from foil-excited heavy ion beams are reported. By observing the target in a direction along the beam axis, an improvement in spectral resolution, δλ/λ, by about a factor of two is achieved, due to the reduced Doppler broadening in this geometry.

To β or not to β: A first look at the Raman spectrum of pure β-UO3

2020 ◽  
Author(s):  
Brianna Barth ◽  
Spano Tyler ◽  
Jeremiah Gruidl ◽  
Michael Lance ◽  
Roger Kapsimalis ◽  
...  
Keyword(s):  
Raman Spectrum
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