Rydberg series in the photoionization spectrum of Pd I

We present the first experimental investigation of the photoionization in Pd I using the synchroton radiation facility of the 800 MeV electron storage ring in Berlin (BESSY) and atomic beam technique. The experiments have been concentrated on the study of the Rydberg series of autoionizing levels $\text{4}\text{d}{}^9\text{(}{}^2\text{D}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{)n}\text{p}$ and nf which lie between the two 4d thresholds.     

The level structure of 114Cd from (n, γ) and (d,p) studies

Gamma rays and conversion electrons have been measured following thermal neutron capture in ¹¹³Cd using the crystal spectrometers GAMS and the β-spectrometer BILL at the High Flux Reactor of the ILL at Grenoble. Primary γ-rays following thermal and average resonance neutron capture at E_n = 2 keV and 24 keV were recorded at the High Flux Beam Reactor at the Brookhaven National Laboratory. The ¹¹³Cd(d, p)¹¹⁴Cd reaction was studied with the Q3D spectrograph at the Munich tandem accelerator. Combining all these experimental results an almost complete level scheme of ¹¹⁴Cd was constructed up to 3.3 MeV including 48 excited levels with spin and parity information. The level scheme is discussed in terms of particle-hole excitations across the Z = 50 closed shell coupled to collective states, as well as in an interacting boson configuration mixing scheme.     

Nitric oxide reduction by CO ON Rh(111): Temperature programmed reaction

The reaction of NO with CO on Rh(111) has been studied with temperature programmed reaction (TPR). Comparisons are made with the reaction of O₂ with CO and the reaction of NO with H₂. The rate-determining step for both CO oxidation reactions is CO(a) + O(a) → CO₂(g). Repulsive interactions between adsorbed CO and adsorbed nitrogen atoms lead to desorption of CO in a peak at 415 K which is in the temperature range where the reaction between CO(a) and O(a) produces CO₂(g). Thus the extent of reaction of CO(a) with NO(a) is less than that between CO(a) and O(a) due to the lower coverage of CO caused by adsorbed N atoms and NO. A similar repulsive interaction between NO(a) and H(a) suppresses the NO + H₂ reaction. CO + NO reaction behavior on Rh(111) is compared to that observed on Pt(111).     

Plasma Beam Discharge in Carbon Dioxide

The paper deals with the dissociation of carbon dioxide in nonequilibrium plasma of a stationary plasma-beam discharge. Experimental results of spectroscopic and probe measurements of plasma parameters are given. Moreover, a mass-spectrometric analysis of gaseous products of the chemical reactions is presented. In addition the measurement of the deposition rate of solid products by means of a quartz oscillator is described. The results show that plasma beam discharge is an effective tool for inducing plasma-chemical reactions.     

Optical homogeneous linewidths in organic glasses below 1 K: a hole-burning study of free-base porphin in 2-methyltetrahydrofuran

Photochemical hole-burning has been used to determine the temperature dependence of the homogeneous linewidth Γ_hom of the 0-0 S₁ - S₀ transition of free-base porphin (H₂P) in 2-methyltetrahydrofuran (MTHF) from T ≈ 5 K down to 0.4 K. A _T^1.30±0.05 dependence for Γ_hom is observed which extrapolates to the lifetime-limited value (≈ 10 MHz) at T ≈ 0.05K.     

Atomic spectroscopy and quantum optics in hollow‐core waveguides

Atomic spectroscopy is a well‐established, integral part of the physicist's toolbox with an extremely broad range of applications ranging from astronomy to single atom quantum optics. While highly desirable, miniaturization of atomic spectroscopy techniques on the chip scale was hampered by the apparent incompatibility of conventional solid‐state integrated optics and gaseous media. Here, the state of the art of atomic spectroscopy in hollow‐core optical waveguides is reviewed The two main approaches to confining light in low index atomic vapors are described: hollow‐core photonic crystal fiber (HC‐PCF) and planar antiresonant reflecting optical waveguides (ARROWs). Waveguide design, fabrication, and characterization are reviewed along with the current performance as compact atomic spectroscopy devices. The article specifically focuses on the realization of quantum interference effects in alkali atoms which may enable radically new optical devices based on low‐level nonlinear interactions on the single photon level for frequency standards and quantum communication systems.     

Passive mode-locking of acentric Yb-doped borate crystals

Passive mode locking of the self-frequency doubling Yb:YAB and Yb:YCOB crystals with a saturable absorber mirror is studied at the fundamental wavelength with diode pumping. All essential polarization orientations including the self-frequency doubling configuration are considered. For the first time sub-90 fs pulses at the fundamental are obtained with both materials and the improvement in terms of pulse length in comparison to previous work is about 2.3 times (Yb:YAB) and 2.8 times (Yb:YCOB). The Yb:YAB laser generates pulses as short as 87 fs at 1050 nm with a 0.4% output coupler. The shortest pulses (76 fs) are obtained with a Y-cut Yb:YCOB for E ∥ Z. With an output coupler of 0.4% the oscillation wavelength is 1056 nm. For E ∥ X the mode-locked Yb:YCOB laser operates on a different Stark transition (at longer wavelengths) than for E ∥ gg and E ∥ Z.     

Subcritical scattering from buried elastic shells

Buried objects have been largely undetectable by traditional high-frequency sonars due to their insignificant bottom penetration. Further, even a high grazing angle sonar approach is vastly limited by the coverage rate dictated by the finite water depth, making the detection and classification of buried objects using low frequency, subcritical sonar an interesting alternative. On the other hand, such a concept would require classification clues different from the traditional high-resolution imaging and shadows to maintain low false alarm rates. A potential alternative, even for buried targets, is classification based on the acoustic signatures of man-made elastic targets. However, the elastic responses of buried and proud targets are significantly different. The objective of this work is to identify, analyze, and explain some of the effects of the sediment and the proximity of the seabed interface on the scattering of sound from completely and partially buried elastic shells. The analysis was performed using focused array processing of data from the GOATS98 experiment carried out jointly by MIT and SACLANTCEN, and a new hybrid modeling capability combining a virtual source-or wave-field superposition-approach with an exact spectral integral representation of the Green's functions for a stratified ocean waveguide, incorporating all multiple scattering between the object and the seabed. Among the principal results is the demonstration of the significant role of structural circumferential waves in converting incident, evanescent waves into backscattered body waves, emanating to the receivers at supercritical grazing angles, in effect making the target appear closer to the sonar than predicted by traditional ray theory.