نتایج جستجو برای: photon spectra

تعداد نتایج: 175255  

2007
D. K. Park

The emission spectra for the spin-1 photon fields are computed when the spacetime is a (4 + n)-dimensional Schwarzschild phase. For the case of the bulk emission we compute the spectra for the vector mode and scalar mode separately. Although the emissivities for the scalar mode is larger than those for the vector mode when n is small, the emissivities for the vector mode photon become dominant ...

Journal: :The journal of physical chemistry. B 2005
Minhaeng Cho Harsha M Vaswani Tobias Brixner Jens Stenger Graham R Fleming

A theoretical description of femtosecond two-dimensional electronic spectroscopy of multichromophoric systems is presented. Applying the stationary phase approximation to the calculation of photon echo spectra and taking into account exciton relaxation processes, we obtain an analytic expression for numerical simulations of time- and frequency-resolved 2D photon echo signals. The delocalization...

2001
Raluca A. Negres Joel M. Hales David J. Hagan Eric W. Van Stryland

We present an experimental technique along with the method of data analysis to give nondegenerate two-photon absorption (2PA) spectra. We use a femtosecond pump pulse and a white-light continuum (WLC) probe to rapidly generate the 2PA spectra of a variety of materials. In order to analyze data taken with this method, the spectral and temporal characteristics of the WLC must be known, along with...

Journal: :Optics letters 2000
Q Zhang M G Müller J Wu M S Feld

We present a method based on photon migration of extracting intrinsic fluorescence spectra from turbid media, using concomitantly measured fluorescence and reflectance. Intrinsic fluorescence is defined as fluorescence that is due only to fluorophores, without interference from the absorbers and scatterers that are present. Application to fluorescence spectra taken with tissue phantoms and huma...

Journal: :Biophysical journal 1967
R T Ross M Calvin

A Planck law relationship between absorption and emission spectra is used to compute the fluorescence spectra of some photosynthetic systems from their absorption spectra. Calculated luminescence spectra of purple bacteria agree well but not perfectly with published experimental spectra. Application of the Planck law relation to published activation spectra for Systems I and II of spinach chlor...

1996
Alice K. Harding Matthew G. Baring

The spectra of soft gamma-ray repeaters (SGRs), with the exception of the March 5, 1979 main burst, are characterized by high-energy cutoffs around 30 keV and low-energy turnovers that are much steeper than a Wien spectrum. Baring (1) found that the spectra of cascades due to photon splitting in a very strong, homogeneous magnetic field can soften spectra and produce good fits to the soft spect...

2002
R. Averbeck

Inclusive transverse momentum spectra of single electrons from Au+Au collisions have been measured at √ s N N = 130 GeV and 200 GeV at midrapidity by the PHENIX experiment at RHIC. After subtraction of background from photon conversions and light hadron decays, the spectra appear consistent with semileptonic decays of charmed particles.

Gholam Reza Ataei Hamed babapour Mohammad Davoudi

Introduction: Previous studies have shown that a Monte Carlo method for the transportations photon beam in medical linear accelerator is a good way. Strip of simulation can be used to measure the dose distribution in phantoms and patients' body. EGSnrc Code is the only code written for use in the field of radiation therapy that has many subset codes that BEAMnrc code is an impo...

Journal: :The Journal of chemical physics 2005
André Fielicke Christian Ratsch Gert von Helden Gerard Meijer

We report experimental infrared spectra of neutral metal clusters in the gas phase. Multiple photon dissociation of the argon complexes of niobium clusters is used to obtain vibrational spectra in the 80-400 cm(-1) region. The observed spectra for Nb(9)Ar(n) (n=1-4) are different for different values of n. This is explained by the presence of two isomers of Nb(9) that have different affinities ...

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