A Scanning Algorithm for Condensed-Phase CARS and Folded Boxcars

1982 ◽  
Vol 36 (4) ◽  
pp. 390-393 ◽  
Author(s):  
L. A. Carreira ◽  
R. Nelson ◽  
M. L. Horovitz ◽  
L. Azarraga
Keyword(s):  
Condensed Phase ◽  
Frequency Limit ◽  
Optical Alignment ◽  
Scanning Algorithm ◽  
Lower Frequency Limit

A scanning algorithm for condensed-phase CARS and folded BOXCARS along with the necessary optical alignment hardware for folded BOXCARS have been developed. Due to the unique geometry of the folded BOXCARS beams, the CARS signal is sufficiently isolated from the pump and Stokes beams such that extended spectra with a lower frequency limit of 70 cm−1 have been obtained.

scholarly journals Solar noise observations from the Alouette satellite

1965 ◽  
Vol 23 ◽  
pp. 357-362
Author(s):  
T. R. Hartz
Keyword(s):  
Solar Radio ◽  
Radio Noise ◽  
Frequency Range ◽  
Sweep Frequency ◽  
Frequency Limit ◽  
Type Iii ◽  
Plausible Model ◽  
Coronal Electron ◽  
Source Velocity ◽  
Lower Frequency Limit

Solar radio noise in the frequency range 1.5 to 10 MHz appears sporadically in the Alouette sweep-frequency recordings above the galactic noise level. The type III bursts can be readily identified, but other spectral types are much more difficult to identify from only the satellite records. Using a plausible model for the coronal electron densities, the Type III frequency drift curves have been interpreted as corresponding to a source velocity in the range 0.1 to 0.15 times the velocity of light. Preliminary estimates have also been made of the coronal temperatures from some of the burst durations.Other solar noise events of longer duration have not been classified other than as enhanced solar noise at this stage. These enhancements frequently show an intensity structure, extending down to the 1.5 MHz lower frequency limit of the equipment. These events are discussed briefly.

Optical Fiber-Based Wave Mixing as a Convenient and Sensitive Laser Analytical Tool for Condensed-Phase Analytes

1998 ◽  
Vol 52 (5) ◽  
pp. 763-769 ◽  
Author(s):  
Jon A. Nunes ◽  
William G. Tong
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Condensed Phase ◽  
Spectroscopic Method ◽  
Spectroscopic Technique ◽  
Wave Mixing ◽  
Small Probe ◽  
Highly Sensitive ◽  
Optical Alignment

A fiber-optic degenerate four-wave mixing (D4WM) probe for the measurement of small absorptions in liquid-phase samples is described. Laser D4WM is a nonlinear laser spectroscopic technique that has proven to be highly sensitive for the detection of trace analytes in condensed-phase media. A significant improvement in the forward-scattering optical arrangement of D4WM is demonstrated by using optical fibers for both laser light input and output. There is considerable flexibility inherent in the design since the system may be used in three configurations: (1) the simplest case of transmitting the signal radiation by optical fiber to the detection electronics, (2) the case of guiding the excitation beams to the analyte by polarization-maintaining optical fibers, and (3) the combination of both. The optical fiber-based D4WM system is shown to be an effective and sensitive laser analytical spectroscopic method for trace analysis, offering advantages such as detection in very small probe volumes, remote and in situ analysis, and convenient and efficient optical alignment enhancements obtained by the use of optical fibers.

Vibrational Circular Dichroism Measurement in the Frequency Range of 800 to 650 cm−1

1987 ◽  
Vol 41 (7) ◽  
pp. 1142-1144 ◽  
Author(s):  
F. Devlin ◽  
P. J. Stephens
Keyword(s):  
Fourier Transform ◽  
Circular Dichroism ◽  
Vibrational Circular Dichroism ◽  
Fourier Transform Spectrometer ◽  
Instrumental Performance ◽  
Frequency Range ◽  
Frequency Limit ◽  
Circular Dichroism Measurement ◽  
Circular Dichroïsm ◽  
Lower Frequency Limit

The development of dispersive instrumentation for the measurement of vibrational circular dichroism (VCD) with a lower frequency limit of ∼650 cm−1 is reported. VCD spectra of 3-methylcyclohexanone, α-pinene, and 3-bromocamphor in the frequency range of 800 to 650 cm−1 are presented to illustrate instrumental performance. The spectra obtained are superior to earlier spectra obtained with the use of a Fourier transform spectrometer.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

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