Two-photon inner-shell transitions in xenon atoms

Abstract

Decay of single-E-shell-vacancy states of xenon atoms by the emission of photon pairs that continuously share the transition energy was studied. The vacancy states were generated by electron-capture decay in ' 'Cs. A pair of high-purity germanium detectors and a fast-slow coincidence system with a (128 X512X512)-channel pulse-height analyzer were used in the measurements. Accurate energy calibration was made by a careful determination of positions of peaks due to crosstalk among the detectors via GeEx rays. Identification of events due to the two-photon decay is based on the shifts of energy sums. From the numbers of events in the ridges, the relative differential probabilities of 2s -+1s, 3s -+1s, 3d -+1s, and 4sd -+1s two-photon decay were derived. They are compared to the values derived from the results of non-relativistic calculations for hydrogen and hydrogenic ions of Shapiro and Breit [Phys. Rev. 113, 179 (1959)], of Tung, Ye, Salamo, and Chan [Phys. Rev. A 30, 1175 (1984)], and of Florescu [Phys. Rev. A 30, 2441(1984],and to the results of the following studies of two-photon decay of single-1t-shell-vacancy states of xenon atoms: a calculation based on the theory of Bannett and Freund [Phys. Rev. Lett. 49, 539 (1982); Phys. Rev. A 30, 299 (1984)], a nonrelativistic calculation of Wu and Li [J. Phys. B 21, 1509Phys. B 21, (1988], and relativistic calculations of Mu and Crasemann [Phys. Rev. Lett. 57, 3039 (1986); Phys. Rev. A 38, 4585 (1988)], and of Tong, Li, Kissel, and Pratt [Phys. Rev. A 42, 1442 (1990)].As expected, no events due to the np~ls two-photon transitions were observed and upper limits are given.PACS number(s): 31.30.Jv, 32.30.Rj, 32.80.Wr INTRA DUCTIQNThe process of emission of photon pairs that continuously share the transition energy is closely related in two atomic systems: hydrogenic systems and many-electron systems with a single inner-shell vacancy. In many systems single-particle and single-hole states have many

Two-Photon Decay in Heavy Atoms and Ions

“…1s and 4s=d ! 1s in xenon ðZ ¼ 54Þ [59], silver ðZ ¼ 47Þ and hafnium ðZ ¼ 72Þ [60]. All these measurements confirmed quite clearly the existence of the two-photon decay branch in singly ionized atoms-and demonstrated that all intermediate states have to be included in the summation whether they are occupied or empty.…”

“…1 ¼ ! 2 and ¼ are shown as solid triangles with error bars for silver ðZ ¼ 47Þ [60], xenon ðZ ¼ 54Þ [59] and hafnium ðZ ¼ 72Þ [60]. For gold the result of the present experiment (!…”

“…[59]) to determine P; the triply differential two-photon transition probability normalized to the total transition probability W K :…”

“…Ilakovac et al [58][59][60] used radioactive sources to generate K vacancies in xenon, silver and hafnium and studied the two-photon decays of these excited atoms. They used a pair of high purity germanium detectors and also applied the photon coincidence technique.…”

Spectral distribution of the 2S →1 S two-photon transition in atoms and few-electron ions

“…Afterwards, several theoretical work, both non-relativistic [13,14] and relativistic [15,16], have been reported. Experimentally, 2S → 1S two-photon decay process has been measured for selective cases in the decay of K -shell vacancy in initially neutral atom using the photon-photon coincidence technique [14,[17][18][19][20][21][22]. In these measurements, the K -shell vacancy is produced by irradiating the targets by photons [14,17,18] or by using radioactive isotopes that preferably decay by nuclear electron capture [19][20][21][22].…”