نتایج جستجو برای: Laser excitation

تعداد نتایج: 240228  

حسین قاسم, , محمد‌حسین مهدیه, , نورالدین محمد‌زاده, ,

  Optogalavanic technique has been used widely in laser spectroscopy. In this paper we have presented the results of an experimental three- step photo- excitation of Gd atom, using optogalvanic technique. Three tunable dye laser pulses were applied to excite the Gd atom in a three-step photo – excitation process. The optogalvanic signal was used to monitor the laser wavelength and efficiency of...

رئیسی, مرتضی, شهریاری, اسماعیل,

Thermal diffusivity of Au nanofluid was measured by using a dual beam mode-mismatched thermal lens method. The samples were prepared in various sizes by utilizing the gamma radiation method. In the dual beam mode-mismatched thermal lens, a diode laser (532 nm) was used as an excitation beam and a He-Ne laser with the beam output at 632.8 nm was used as a probe beam. Thermal diffusivity of gold...

Amirabolfazl Soratgar Firooz Bakhtiari-Nejad, Mahdi Vahabi Maysam Mirzaei

Determination and analysis of vibration behavior of structures for at least first few natural frequencies and mode shapes needs several sensors to be connected at different non node points and exciting the structure at one point. Other method for determination of first few mode shapes is to excite several points of the structure at once and sensing the response from one point.  Both methods nee...

In this paper, we have simulated the excitation of wake fields in the interaction of an intensive laser pulses having Half-Sine and Gaussian time envelopes with a fully ionized cold plasma using particle in cell (PIC) method. We investigated the dependency of wake filed amplitude to different laser and plasma parameters such as laser wavelength, pulse duration and electron number density. In ad...

2010
Stanley M. Smith Dmitri A. Romanov George Heck H. Bernhard Schlegel Robert J. Levis

Time-dependent Hartree-Fock simulations for a linear triatomic molecular monocation (CO2) interacting with a 5 fs, 800 nm, strong field laser pulse were performed to explore the excitation mechanisms in a molecular cation. Fourier analysis of the time-dependent residual dipole moment reveal a nonmonotonic behavior in the amplitude of the 5.18 eV feature in the excitation spectra of the molecula...

Journal: :Applied optics 1988
P Andresen A Bath W Gröger H W Lülf G Meijer J J Meulen

A new method for instantaneous temperature field measurements based on LIF studies of OH, O(2), and H(2)O in an open atmospheric flame with a tunable excimer laser is suggested. In this method the crucial problem of quenching at higher pressures is almost completely eliminated by excitation to a fast predissociating state. The various possible excitation and fluorescence processes that can be i...

2006
A. D. Kondorskiy

The possibility of achieving highly selective excitation of low metastable states of hydrogen and helium atoms by using short laser pulses with reasonable parameters is demonstrated theoretically. Interactions of atoms with the laser field are studied by solving the close-coupling equations without discretization. The parameters of laser pulses are calculated using different kinds of optimizati...

2000
M. A. El-Sayed

Gold nanorods have been found to change their shape after excitation with intense pulsed laser irradiation. The final irradiation products strongly depend on the energy of the laser pulse as well as on its width. We performed a series of measurements in which the excitation power was varied over the range of the output power of an amplified femtosecond laser system producing pulses of 100 fs du...

2009
A. T. Hammack L. V. Butov A. L. Ivanov A. C. Gossard

We report on the kinetics of the inner ring in the exciton emission pattern. The formation time of the inner ring following the onset of the laser excitation is found to be about 30 ns. The inner ring is also found to disappear within 4 ns after the laser termination. The latter process is accompanied by a jump in the photoluminescence PL intensity. The spatial dependence of the PL jump indicat...

E. Mohajerani, H. Shahroosvand, I. A. Alidokht, N. Safari, S. Osati,

Electronic absorption, florescence excitation and AFM studies of selected homogeneous solutions and thin films of mesotetrakis (parahydroxyphenyl) porphyrin (THPP) (1), mesotetrakis (2, 3- dihydroxyphenyl) porphyrin 2, 3-OHPP) (2), mesotetrakis (3, 4-dihydroxyphenyl) porphyrin (3, 4-OHPP) (3) as well as Zn(II) derivative of 2, 3-OHPP (4) under UV lamp and green laser irradiation (532 nm) are ac...

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