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1.
Cumulant functions are introduced to describe the statistical state of a radiation field. These functions are simply related
to the optical coherence functions but have some interesting features. It is shown that if the cumulant functions of all orders
greater than some numberN
0 vanish then they also vanish for all orders greater than 2. Thermal field is the only field having this property. This property
holds whether the field is described by a classical stochastic process or by a quantum density operator. Further the particular
operator ordering used in defining these cumulant functions for the quantized field affects only the second order cumulant
function. To describe the statistical state of a vector field such as partially polarized or unpolarized radiation, one would
need to introduce cumulant tensors. 相似文献
2.
MA Freitas CL Hendrickson AG Marshall 《Rapid communications in mass spectrometry : RCM》1999,13(15):1639-1642
We present a novel approach for the determination of activation energy for the unimolecular dissociation of a large (>50 atoms) ion, based on measurement of the unimolecular dissociation rate constant as a function of continuous-wave CO(2) laser intensity. Following a short ( approximately 1 s) induction period, CO(2) laser irradiation produces an essentially blackbody internal energy distribution, whose 'temperature' varies inversely with laser intensity. The only currently available method for measuring such activation energies is blackbody infrared radiative dissociation (BIRD). Compared with BIRD, FRAGMENT: (a) eliminates the need to heat the surrounding ion trap and vacuum chamber to each of several temperatures (each requiring hours for temperature equilibration); (b) offers a three-fold wider range of effective blackbody temperature; and (c) extends the range of applications to include initially cold ions (e.g., gas-phase H/D exchange). Our FRAGMENT-determined activation energy for dissociation of protonated bradykinin, 1.2 +/- 0.1 eV, agrees within experimental error to the value, 1.3 +/- 0.1 eV, previously reported by Williams et al. from BIRD experiments. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
3.
K. Jessen W. Andrejtscheff M. Bergström P. von Brentano A. Dewald B. Herskind H. Meise C. Schumacher G. Sletten O. Stuch D. Weißhaar I. Wiedenhöver J. Wrzesinski 《The European Physical Journal A - Hadrons and Nuclei》1999,4(1):9-10
A new high-spin isomer in 145Sm was observed by in-beam γ-ray spectroscopy with the reaction 122Sn(27Al,3np) at 127 MeV performed at the Nordball multi-detector array in Roskilde. The excitation energy of the isomer was determined
to be E
x= 11147 keV, and using the generalized centroid-shift method its half-life was found to be T
1/2= (7.4 ± 1.0) ns.
Received: 23 October 1998 相似文献
4.
K. Jessen M. Bergström P. von Brentano A. Dewald B. Herskind H. Meise C. Schumacher G. Sletten O. Stuck D. Weißhaar I. Wiedenhöver J. Wrzesinski 《The European Physical Journal A - Hadrons and Nuclei》1998,2(2):113-114
An in-beam experiment with the reaction 122Sn(27Al,4np) at 127 MeV was performed at the Nordball multi-detector array in Roskilde. It provided evidence for a new high-spin
isomer in 144Sm. This isomer with T
1/2= (2.6 ± 0.5) ns at an excitation energy E
x= 9232 keV seems to belong to a family of isomers of similar configuration in neighbouring N= 82 nuclei.
Received: 16 November 1997 相似文献
5.
K. Bharuth-Ram G. Lo Bianco P. Paruzzi A. Dewald J. Wrzesinski K.O. Zell P. Von Brentano 《Nuclear Physics A》1984,427(3):451-459
The lifetime of the 206Tl 2? state at 266 keV has been measured by the delayed coincidence technique. The state was populated via the γ-decay of high-lying states excited in the 205Tl (d, p)206Tl reaction at Ed = 9.0 MeV. Delayed coincidences between a Si surface-barrier detector and a Ge(Li) detector resulted in a mean life for the 266 keV level of τ = 3.3(2) ns. The deduced B(E2) value of 171 (11) e2 · fm4 indicates strong configuration mixing of two-hole states in this level. 相似文献
6.
T. Shizuma G. Sletten R. A. Bark N. L. Gjørup H. J. Jensen S. Mitarai M. Piiparinen J. Wrzesinski 《Zeitschrift für Physik A Hadrons and Nuclei》1997,359(3):229-230
High-spin states in 185Re have been studied using the 176Yb(13C,p3n) reaction at 65 MeV. Levels up to spin (37/2) h? at E x = 4.799 MeV have been identified. Among them two levels were observed with half-lives of 6 ± 2 ns and 123 ± 23 ns. 相似文献
7.
Sukesh Roy Paul J. Wrzesinski Dmitry Pestov Marcos Dantus James R. Gord 《Journal of Raman spectroscopy : JRS》2010,41(10):1194-1199
Coherent anti‐Stokes Raman scattering (CARS) spectroscopy of gas‐phase CO2 is demonstrated using a single femtosecond (fs) laser beam. A shaped ultrashort laser pulse with a transform‐limited temporal width of ∼7 fs and spectral bandwidth of ∼225 nm (∼3500 cm−1) is employed for simultaneous excitation of the CO2 Fermi dyads at ∼1285 and ∼1388 cm−1. CARS signal intensities for the two Raman transitions and their ratio as a function of pressure are presented. The signal‐to‐noise ratio of the single beam–generated CO2 CARS signal is sufficient to perform concentration measurements at a rate of 1 kHz. The implications of these experiments for measuring CO2 concentrations and rapid pressure fluctuations in hypersonic and detonation‐based chemically reacting flows are also discussed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
8.
K. Jessen M. Bergström P. von Brentano A. Dewald B. Herskind H. Meise C. Schumacher G. Sletten O. Stuch D. Weißhaar I. Wiedenhöver J. Wrzesinski 《Zeitschrift für Physik A Hadrons and Nuclei》1997,357(3):245-246
In 145Eu a high-spin isomer with E level = 8528 keV and T 1/2 = (3.7 ± 0.4) ns has been observed. The data were obtained by in-beam γ-ray spectroscopy using the reaction 122Sn(27Al,4n)145Eu at 127 MeV performed at the NORD-BALL spectrometer in Roskilde. 相似文献
9.
S. Leoni A. Bracco T. Døssing B. Herskind J.C. Lisle M. Matsuo E. Vigezzi J. Wrzesinski 《The European Physical Journal A - Hadrons and Nuclei》1999,4(3):229-231
The number of discrete rotational bands in the nucleus 168Yb is obtained by a fluctuation analysis of the rotational ridge structure in double and triple γ coincidence matrices. The
data are compared with cranked shell model calculations including a surface delta interaction. It is found that the number
of calculated bands strongly depends on the interaction strength V0, and agreement between data and calculations supports the standard value V0= 27.5/A MeV.
Received: 11 January 1999 相似文献
10.
铌酸锶钡薄膜的微结构与电光性能的研究 总被引:3,自引:1,他引:2
本文叙述了使用溶胶凝胶法在MgO(0 0 1)的衬底上制备铌酸锶钡薄膜的过程 ,膜层厚度可达 5 μm。通过X射线衍射、摇摆曲线、扫描、拉曼散射光谱等方法研究了薄膜的微结构性能 ,实验发现 ,铌酸锶钡薄膜具有了较好的 (0 0 1)方向的优先取向性能 ,并且随着薄膜厚度的增加 ,其晶体取向性也会随之不断改进。熔石英的透明衬底上生长的SBN薄膜具有较大的电致双折射效应 ,其有效电光系数能够高达 6 6 2× 10 -11m/V。 相似文献