Raman spectra of Carbon Tetrachloride in Methanol solutions were
measured. Spectral lines n1 (symmetric stretch vibrations), n3 (asymmetric
stretch vibrations) of Carbon Tetrachloride were analyzed. The Raman spectra
were fitted using Peak-Fit sof
tware applying a sum of Gaussian and Lorentzian
components. Results indicate that, there is a clear difference in the behavior of
peak position and width of the two type of vibrations with varying the
structural composition of the surrounding environment due to varying of the
methanol concentration. On the other hand we found that a similarity in the
dependence of the intensity of spectral lines on the concentration of methanol,
with a high degree of non-linearity.
The retroreflection phenomenon takes place in all optical and optoelectronical
devices and systems that use optical detectors, mirrors, CCD
cameras, filters, or glasses in the focal point and in the optical measurement
instruments, in general, pro
vided that some of their optical components are
retroreflective to light even for small apertures.
The article studies a precise method to measure the retroreflection index of
optical, opto-electronical systems, and treats the optical retroreflections which
are used in applied research of light with various lasers such as: Nd:YAG first
and second harmonics, He-Ne, and laser diodes.
We have studies the conformity of our results to the theory of
retroreflectors. We found that the retroreflection coefficient depends on laser
wavelength. The article points out that at 532nm laser wavelength the
retroreflection is greater than at 1064nm laser wavelength.
The results of this paper can be used in applied research, and led to
description of a mathematical relationship between the retroreflection index
and laser wavelength.
Photonic crystals is a low-loss periodic medium with periodic changes of
refractive index, which is used to control the light.
Theoretically, Photonic crystals can be studied using Maxwell equations, but
it’s difficult to find a general analytical
solution for these equations, since we
are dealing with vectors. So we resort to the numerical solutions for Maxwell’s
equations to calculate the reflection and transmission coefficients and the
Photonic band gap.
There are wide uses of tin oxide thin films, especially in the field of
transparent conductors, solar cells, gas sensors and piezoelectric materials.
Laser deposition is considered one of the most important techniques followed to
obtain these film
s. In this research, we develop a technique to obtain
homogeneous thin films of tin oxide depending on vaporization of pile targets of
this oxide by continuous CO2 laser in the atmosphere, with a fan which
guarantees obtaining homogenous films. Some of these films were annealed in
different conditions. The optical microscope images revealed the presence of
high degree of homogeneity, while the X-Ray study showed different
crystallization grain orientations which depend on the preparation conditions.
The preferred direction is (110). The optical absorption gives information
about the value of the effective band gal for the samples before and after
thermal annealing. We have found that some films have Eg = 3.2 ev. before
annealing, and after long annealing they have Eg=1.3ev. In addition, the hard
annealed thin films reveal anisotropy in the optical and electrical.
Characteristics, they have different absorption coefficients in two
perpendicular directions, also there is an electrical resistance anisotropy along
these two directions especially after hard annealing. The Eb was 0.73 ev before
annealing, it became 0.37 ev for one direction and 0.32 ev for the other
direction.
Atmospheric temperature increases after sunrise to reach its maximum at
approximately ٢ hours from midday. The temperature variation curve agrees
with the intensity curve of incident solar radiation on the earth surface, but
with delay time (tow h
our) proportional to the parameters atmosphere and
materials.
During eclipse of sun, the intensity of solar radiation decreased, and as a
consequence, this affects many atmospheric processes, such as temperature of
air and wind cycles. These changes can be studied as variations of solar
radiation density, which occurs in the short time of the eclipse.
These variations can be observed by a spectroscopic study, was the subject
of the Damascus university scientific group to studying the total eclipse in Ain-
Dewar, which is located at northeast of Syria on ١١-th of August ١٩٩٩.
The variations happened in solar spectrum and in the earth atmosphere
were recorded and discussed in detail. The recorded diagrams and spectrum
were analyzed for the estimation of the magnitude of radiation energy, which
was screened during eclipse. They result in the estimation of energy loss by the
atmosphere and its parameters like temperature and wind movement.
It was shown, that ٦٠٪ of the total solar energy were screened during
eclipse, and this was sufficient to cause many changes in wind velocity and
temperature of the atmosphere. Because of the eclipse line and neighboring
areas considered to be connected with thermodynamic system, thus the energy
changes will decrease in the atmosphere, Sowe didn’t calculate it.
The aim of this paper is to test the influence of the laser brightness on the
retina of eye of lacerta laevis, and the value of the distortion or damage in the
construction of photoreceptors (Cones), which are responsible of the viewing
process or
in the pigmentary epithelial layer which protect from the high light
intensity.
On the other hand, the continuation of the exposure to the He- Ne laser
beam the number of the damaged cells, that causes the loss of entire
photoreceptor layer. The results show similar effects at specular reflection.
Hence, it is very important to pay attention to the hazard emerged from the
laser beam in visible range, which requires to apply the special goggles, as well
as to keep the laser pointers out of reach of children.
