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1.
The collisional shifts and widths of several P-branch spectral lines in the fundamental band of CO-Ar have been measured at temperatures between 214 and 324 K and pressures between 0.025 and 1 atm. The widths have been determined using a line shape model based on the solution of the transport/relaxation equation for the appropriate off-diagonal element of the density matrix. The model uses a realistic molecular potential energy surface to calculate the speed dependence of the collisional broadening, and a rigid sphere potential to calculate the translational motion. It is found that both the shifting and broadening coefficients follow a power law dependence on the temperature. Additionally, it is demonstrated that studies have tended to overestimate the accuracy of collisional widths when the line shape model used to obtain the widths involves multiple fitted line shape parameters or fails to fit the measured spectra within the experimental noise. 相似文献
2.
Ch. Lisdat N. Vanhaecke D. Comparat P. Pillet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):299-309
Two-photon photoassociation spectra in a Λ-type excitation scheme are analysed under the systematically varied experimental conditions of frequency detunings and laser
intensities. Line shape fits are presented as well as the investigation of intensity and detuning dependent line shifts. From
both we determine the attained spectroscopic precision, that is corrected for a systematic line shift due to the thermal distribution
of atoms in the trap. An energy correction for this effect is given. Information about the feasibility of generating translationally
cold molecules in a well defined rotational and vibrational level by the photoassociation process is derived from the analysis.
Received 21 May 2002 Published online 15 October 2002
RID="a"
ID="a"Current address e-mail: christian.lisdat@ptb.de
RID="b"
ID="b"e-mail: pierre.pillet@lac.u-psud.fr 相似文献
3.
I.?A.?Pshenichnov B.?L.?Berman W.?J.?BriscoeEmail author C.?Cetina G.?Feldman P.?Heimberg A.?S.?Iljinov I.?I.?Strakovsky 《The European Physical Journal A - Hadrons and Nuclei》2005,24(1):69-84
We have calculated the fission probabilities for 237Np, 233, 235, 238U, 232Th, and natPb following the absorption of photons with energies from 68 MeV to 3.77 GeV using the RELDIS Monte Carlo code. This code implements the cascade-evaporation-fission model of intermediate-energy photonuclear reactions. It includes multiparticle production in photoreactions on intranuclear nucleons, pre-equilibrium emission, and the statistical decay of excited residual nuclei via competition of evaporation, fission, and multifragmentation processes. The calculations show that in the GeV energy region the fission process is not solely responsible for the entire total photoabsorption cross-section, even for the actinides. The fission probabilities are 80-95% for 233U, 235U, and 237Np, 70-80% for 238U, and only 55-70% for 232Th. This is because certain residual nuclei that are created by deep photospallation at GeV photon energies have relatively low fission probabilities. The results of those model calculations are in reasonable agreement (at the 10% level) with recent experimental data on relative photofission cross-sections for 237Np and 233, 235, 238U (but not for 232Th or natPb) from the Saskatchewan and Jefferson Laboratories over a very wide range in photon energy. Using our calculated fission probabilities plus the total photoabsorption cross-sections per nucleon, estimated from previous cross-section data for nuclei from C to Pb, we can infer absolute photofission cross-sections for the actinide nuclei and compare them with the SAL and JLab results. The resulting discrepancies, however, clearly demonstrate the need for direct measurement of the total photoabsorption cross-sections for the heavy actinides. 相似文献
4.
V.C. Selvaraju S. Asokan V. Srinivasan 《Applied Physics A: Materials Science & Processing》2003,77(1):149-153
The I–V characteristics of bulk As40Te60-xSex and As35Te65-xSex glasses have been studied with a current sweep of 0–18 mA-0, over a wide range of compositions (4≤x≤22). All the glasses
studied showed a threshold electrical switching behaviour. The number of switching cycles withstood by the samples has been
found to depend on the ON-state current. It is seen that the switching voltages increase with increase in selenium content.
Further, the switching voltages are found to be almost independent of the thickness of the sample (d), in the range 0.18–0.3 mm.
Also, the switching voltages and the number of switching cycles withstood by the samples are found to decrease with temperature.
Received: 6 November 2002 / Accepted: 8 November 2002 / Published online: 29 January 2003
RID="*"
ID="*"Corresponding author. Fax: +91-80/360-0135, E-mail: sasokan@isu.iisc.ernet.in 相似文献
5.
6.
Z. T. Alwahabi J. Zetterberg Z. S. Li M. Aldén 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(1):41-47
High resolution Infrared Polarisation Spectroscopy (IRPS) and Infrared Laser
Induced Fluorescence (IRLIF) techniques were used to probe CO2/N2
binary gas mixture at atmospheric pressure and ambient temperature. The
probed CO2 molecules were prepared by laser excitation to an overtone
and combination ro-vibrational state (1201, J=15) of CO2, centred
at 4988.6612 cm-1. IRPS and IRLIF line profiles were recorded for
several CO2/N2 binary mixtures. The observed IRLIF line shapes
have the expected Lorentzian form while the observed IRPS line shapes are
narrower by a factor of two than those recorded with the IRLIF and appear to
have a Lorentzian-cubed profile. The recorded line profiles provide
measurements of the pressure-broadening coefficient directly at atmospheric
pressure. The Full-Width-Half-Maxima (FWHM) pressure broadening coefficients
are measured, based on IRLIF, to be 0.2174±0.0092 cm-1atm-1 and 0.1327
±0.0077 cm-1atm-1 for self- and N2 collision broadening,
respectively. The broadening coefficients obtained based on IRPS were
measured to be ~8% larger than those obtained with IRLIF. 相似文献
7.
Strong enhancement of spontaneous emission in amorphous-silicon-nitride photonic crystal based coupled-microcavity structures 总被引:1,自引:0,他引:1
M. Bayindir S. Tanriseven A. Aydinli E. Ozbay 《Applied Physics A: Materials Science & Processing》2001,72(1):125-127
We investigated photoluminescence (PL) from one-dimensional photonic band gap structures. The photonic crystals, a Fabry–Perot
(FP) resonator and a coupled-microcavity (CMC) structure, were fabricated by using alternating hydrogenated amorphous-silicon-nitride
and hydrogenated amorphous-silicon-oxide layers. It was observed that these structures strongly modify the PL spectra from
optically active amorphous-silicon-nitride thin films. Narrow-band and wide-band PL spectra were achieved in the FP microcavity
and the CMC structure, respectively. The angle dependence of PL peak of the FP resonator was also investigated. We also observed
that the spontaneous emission increased drastically at the coupled-cavity band edge of the CMC structure due to extremely
low group velocity and long photon lifetime. The measurements agree well with the transfer-matrix method results and the prediction
of the tight-binding approximation.
Received: 8 March 2001 / Accepted: 17 March 2001 / Published online: 23 May 2001 相似文献
8.
M. De Rosa C. Nardini C. Piccolo C. Corsi F. D’Amato 《Applied physics. B, Lasers and optics》2001,72(2):245-248
High-resolution spectroscopic measurements were made using distributed feedback diode lasers. We measured line strength and
pressure-induced broadening and shift for two lines, R(3) and P(4), of the first overtone (2?0) ro-vibrational band, for the
two isotopomers H35Cl and H37Cl, according to their natural abundances; measurements were also made in the presence of foreign gases. Comparison was made
with available data when possible.
Received: 29 February 2000 / Published online: 8 November 2000 相似文献
9.
Beryllium‐nitride (BeN) thin films were prepared by sputtering a Be target in an atmosphere of pure nitrogen. The films were doped with samarium simply by placing a piece of Sm metal on the surface of the Be target. Under these deposition conditions the films present an amorphous structure and an optical bandgap of approx. 4 eV. They also exhibit visible light emission due to Sm3+ ions as a result of either photon or electron excitation. The present experimental results show that amorphous BeN films are suitable, and efficient, III‐nitride hosts for rare‐earth doping purposes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
10.
R.M. Xie H.B. Fu X.H. Ji Z.H. Chen J.N. Yao 《Applied Physics A: Materials Science & Processing》2002,74(2):239-242
4,4′-dibromobiphenyl nanocrystals with different sizes in the range from 20 nm to 300 nm were prepared by the reprecipitation
method. It was found that their absorption peaks experienced a red shift while the size of the nanocrystals increased. Through
analyzing these spectra of the nanocrystals with different sizes, it is suggested that this size-dependent optical property
is contributed by two factors, the size effect and the J-aggregate formation.
Received: 28 August 2000 / Accepted: 2 March 2001 / Published online: 23 May 2001 相似文献