The J = 2 ortho levels of the v = 0 to 6 np singlet Rydberg series of molecular hydrogen revisited.

The energies of the J = 2 ortho levels of the v = 0 to 6 Rydberg np singlet series of molecular hydrogen with absolute intensities of the R(1) and P(3) absorption lines were measured by a high-resolution synchrotron radiation experiment and calculated through a full ab initio multi-channel quantum defect approach.

The J = 1 para levels of the v = 0 to 6 np singlet Rydberg series of molecular hydrogen revisited.

The energies and the widths of the J = 1 para levels of the v = 0 to 6 Rydberg np singlet series of molecular hydrogen with absolute intensities of the R(0) and P(2) absorption lines were measured by a high - resolution synchrotron radiation experiment and calculated through a full ab initio multichannel quantum defect theory approach. On the basis of the agreement between theory and experiment, 31 levels were either reassigned or assigned for the first time.

The transition probabilities from the ground state to the excited J = 0 1Σu(+) levels of H2: measurements and ab initio quantum defect study.

The energies, widths and absolute intensities of the P(1) v'' = 0, J'' = 1 absorption transitions of H(2) have been measured in the spectral range of 81-75 nm using monochromatized synchrotron radiation. This work completes and extends previous observations, in particular those of Herzberg and Jungen [J. Mol. Spectrosc. 41, 425 (1972)]. Ab initio multichannel quantum defect theory (MQDT) is used to corroborate the spectral analysis of the experimental data. Line intensities and decay widths are also calculated using MQDT.

Symmetry-forbidden electronic state interference observed in angularly resolved NO+ (A 1Π) deexcitation spectra of the N*O(2σ(-1)2π(2)) resonance.

Quantum mechanical interference between different pathways in inner-shell resonance excitation-deexcitation spectra is a realization of a double-slit experiment on the atomic scale. If the intermediate inner-shell resonances are of different symmetries, this interference is symmetry forbidden in the solid-angle-averaged or magic-angle-recorded deexcitation spectra. It has, however, been suggested that interference may by observable in off-magic-angle-recorded spectra. Here, we prove this interference in angularly resolved deexcitation spectra of the 2σ(-1)2π(2)(2Δ,2Σ±) resonances of N*O by a quantitative comparison between ab initio calculations and experiment.

Neutral dissociation of the I, I', and I" vibronic progressions of O2.

It is suggested that the main mechanism for neutral dissociation of the I, I('), and I(") vibronic progressions in O(2) is due to their interaction with the vibrational continuum of the 1pi(u) (-1)(A (2)Pi(u))3ssigma(g) (3)Pi(u)(v(epsilon)) Rydberg state (J state) leading to the formation of the O(2p(4) (3)P)+O( *)(2p(3)((4)S)3s (3)S) fragments. In order to justify this, the O I 2p(3)((4)S)3s (3)S-->2p(4) (3)P fluorescence emission cross section following the neutral dissociation of the O(2) 1pi(u) (-1)(a (4)Pi(u))4ssigma(g)/3ddelta(g)/3dsigma(g) (3)Pi(u)(v) Rydberg states is simulated in the exciting-photon energy range of 14.636-16.105 eV. The results of high-resolution measurements (H. Liebel et al., J. Phys. B 34, 2581 (2001)) can be reproduced if a small adjustment of the computed potential curve of the J state is applied. Non-Franck-Condon resonant intensity distributions of the I, I('), and I(") progressions observed in the experiment are qualitatively explained by the presence of the O(2) 1pi(g) (-1)(X (2)Pi(g))npsigma(u)/nfsigma(u)/nfdelta(u) (3)Pi(u) perturber states. Present calculations allow to decide between two different assignments of the I, I('), and I(") states available in literature.

H2 superexcited states: experimental and theoretical characterization of their competing decay-channel fluorescence, dissociation, and ionization.

The absolute cross sections for the competing decay channels fluorescence, dissociation, and ionization of photoexcited long-lived superexcited H(2) molecular levels have been measured from the ionization threshold of H(2) up to the H(1s)+H(n=3) dissociation limit. The total and partial natural widths of these levels have been determined. Good agreement is found with first principles calculations carried out by multichannel quantum defect theory. The calculations reproduce the balance between the competing decay processes as well as its substantial level-to-level evolution.

The study of the D(') (1)Pi(u) state of H(2): transition probabilities from the ground state, predissociation yields, and natural linewidths.

The absorption spectrum of the H(2) molecule was studied at high resolution in the 81-72 nm spectral range. A detailed analysis of the D(') (1)Pi(u)-->X (1)Sigma(g) (+) electronic band system is reported. In the spectrum, more than 70 new lines were assigned. For wavelengths longer than 75 nm, the D(') (1)Pi(u) (+) and (1)Pi(u) (-) components show a clearly different behavior: Tauhe (1)Pi(u) (+) one dissociates into H(1s)+H(n=2) whereas the (1)Pi(u) (-) one leads to molecular fluorescence. For shorter wavelengths, both components are predissociated into H(1s)+H(n=3). The predissociation yields, the dissociation widths, and the absolute values of the transition probabilities were measured over the vibrational progression from v(')=3 to 17, i.e., up to the dissociation limit. The comparison between these absolute transition probabilities and the values calculated in the adiabatic and nonadiabatic approximations demonstrates clearly the importance of nonadiabatic couplings.

Study of the B"B 1Sigmau+ state of H2: transition probabilities from the ground state, dissociative widths, and Fano parameters.

The transition probabilities, the dissociation widths, and the associated Fano parameters for rovibronic lines with J"=0,...,3 of the absorption bands of the B"B 1Sigmau+ state out of the X 1Sigmag+ v"=0 ground state were measured over the complete vibrational progression, showing clearly that only the inner-well state with B" 4psigma character can absorb vuv light and predissociate efficiently. The absolute values of these transition probablities, predissociation widths, and Fano parameters were found to agree well with ab initio calculations if one takes into account that the calculations neglect nonadiabatic couplings.

Cross sections for the ionization continuum of H2 in the 15.3-17.2 eV energy range.

The absolute values for the cross sections of the ionization continuum of H2 had been measured at low energy (15.3-17.2 eV) Both absorption and ionization spectra were simultaneously recorded with linear response and absolute values, using a 10 m normal incidence monochromator installed on a synchrotron undulator beamline. The vibrational thresholds can be clearly seen as steps in the experimental data. The agreement between experimental values and theoretical ones is very good except around the first and second vibrational thresholds where the experimental data exceed the theoretical ones.

Raman regime energy dependence of alignment and orientation of KrII states populated by resonant Auger effect.

The energy dependencies of alignment parameters A20 for KrII 4p(4)5p states after the Auger decay of the KrI 3d(9)np resonances were investigated theoretically and experimentally for the first time in the Raman regime with the bandwidth of the exciting radiation (deltaE(FWHM)=20 meV) smaller than the natural width of the resonances (Gamma approximately 80 meV). The observed energy dependence is due to the in-terference between the different resonance channels and the direct photoionization channel. A strong energy dependence for both the orientation parameter O10 and the photoelectron angular distribution parameter beta(el) is also predicted.

Immunohistochemical and electron microscopic study of interaction of Yersinia enterocolitica serotype O8 with intestinal mucosa during experimental enteritis.

The experimental infection of mice with Yersinia enterocolitica serotype O8 was investigated in a quantitative and histological study. The course of bacterial penetration and spreading was precisely determined by immunohistochemical staining. After oral administration, the bacteria passed the epithelial barrier of the ileum and spread into the lamina propria. By preference they entered Peyer's patches, which were about 1,000 times more heavily colonized than the surrounding epithelium of a comparable surface area. The bacteria proliferated in the follicles, from which they spread into the lamina propria of the villi. At either site most of the bacteria multiplied extracellularly, with only a small percentage observed to be present within the phagocytes. The bacteria did not appear to be able to pass the intact basement membrane; hence, the integrity of the basement membrane is likely to play a role in determining the route of entry and limit of spread of Y. enterocolitica infection.