100,548 research outputs found
Observation of enhanced soft x-ray emission using nitrogen clusters ionized by intense, femtosecond laser
No full textWe report soft x-ray spectra (5-18 nm) from a cryogenically cooled nitrogen gas jet irradiated by 28-fs-laser pulses at an intensity of similar to7 x 10(16) W/cm(2). While the time-integrated spectrum obtained at room temperature showed exclusively transitions in N4+ ions, spectral lines from N5+ and N6+ charge states appeared with cooling. Rapid, nonlinear increase of x-ray emission on lines from N4+, N5+, and N6+ has been observed by lowering the preexpansion gas temperature. (C) 2003 American Institute of Physics.This research was supported by the Ministry of Science
and Technology of Korea through the Creative Research Initiative
Program. The visit of T. Mocek to KAIST was supported
by the Korea Science and Engineering Foundation
and by the Czech Ministry of Education, Youth and Sports
through the Laser Plasma Research Center (Project LN00A100
Exposed sets in potential theory☆☆The work is part of the research project MSM 0021620839 financed by MSMT.
No full textAbstractLet U be a relatively compact open subset of a harmonic space, and H(U) be the function space of all continuous functions on U¯ which are harmonic on U. We give a complete characterization of the H(U)-exposed subsets of U¯. This extends the results of [J. Lukeš, T. Mocek, M. Smrčka, J. Spurný, Choquet like sets in function spaces, Bull. Sci. Math. 127 (2003) 397–437]
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
Soft-x-ray emission from small-sized Ne clusters heated by intense, femtosecond laser pulses
No full textSoft-x-ray emission from a cryogenically cooled Ne jet irradiated; by intense, 25-fs laser pulses was measured. The Ne spectrum started to drastically change in emitting ions from Ne5+ to Ne7+ below the preexpansion temperature of - 120 degrees C. The significant change in the spectrum is attributed to the collisional heating of small-sized Ne clusters formed in the cooled jet. The increase of the laser pulse length from 25 fs to 100 fs resulted in further increase of x-ray emission from Ne7+ states.This research was supported by the Ministry of Science and Technology of Korea through the Creative Research Initiative Program
Enhancement of soft x-ray emission from a cryogenically cooled Ar gas jet irradiated by 25 fs laser pulse
No full textSoft x-ray spectra (40-180 Angstrom) produced by the interaction of 25 fs laser pulses at an intensity of similar to 7 x 10(16) W/cm(2) with a cryogenically cooled Ar gas jet have been measured. New spectral lines from Ar8+ and Ar9+ charge states appeared with decreasing gas temperature. Nonlinear increase of x-ray line emission from Ar7+, Ar8+, and Ar9+ was observed with cooling, which saturated below certain temperature. The drastic change in the spectrum is attributed to efficient collisional heating and collisional ionization of growing (10(2)-10(3) atoms) Ar clusters from the cooled jet. (C) 2000 American Institute of Physics. [S0003-6951(00)02614-0].This research was supported by the Ministry of Science and Technology of Korea through the Creative Research Initiative Program
Investigation of soft X-ray emission from Ar clusters heated by ultrashort laser pulses
No full textWe report soft X-ray spectra (4-18 nm) produced by the interaction of 25-100-fs laser pulses at an intensity of up to 7 X 10(16) W/cm(2) with a cryogenically cooled Ar gas jet. New spectral lines from Ar8+, Ar9+, and Ar10+ charge states appeared with decreasing preexpansion gas temperature. A nonlinear increase of X-ray line emission from Ar7+, Ar8+, and Ar9+ was observed with cooling, which saturated below a certain temperature. The drastic change in the spectrum is attributed to efficient collisional heating and collisional ionization of growing, small- to medium-sized (10(2)-10(3) atoms) Ar clusters from the cooled jet. When the laser pulse was extended from 25 to 100 fs we observed considerably stronger emission on lines from high charge states, such as Ar8+, Ar9+, and Ar10+, which suggests that the resonance absorption condition could be reached for the 100-fs pulse
Interaction of intense, femtosecond laser pulse with small-sized Ne clusters
No full textWe report the first observation of X-ray emission (4 - 18 nm) from small-sized Ne clusters heated by high-intensity, 25-100 A laser pulses. The Ne spectrum started to drastically change in emitting ions from Ne5+ to Ne7+ below the pre-expansion temperature of -120 degreesC. The significant change in the spectrum is attributed to the collisional heating of small-sized Ne clusters formed in the cryogenically cooled gas jet. Though the size of Ne clusters in our experiment is estimated to be quite small, i.e. a few tens of atoms per cluster, and thus they were undetectable by the standard Rayleigh scattering technique, the. appearance of spectral lines of Ne7+ ions presented clear evidence of collisional heating that occurred in near-solid-density cluster. By extending the laser pulse length from 25 fs to 100 fs, considerably higher X-ray yield from the highest charge state Ne7+ was observed in the covered spectral region, showing more efficient absorption of 100 fs laser pulse
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