Angular correlation between photoelectrons and auger electrons from K-shell ionization of neon.

We have used cold target recoil ion momentum spectroscopy to study the continuum correlation between the photoelectron of core-photoionized neon and the subsequent Auger electron. We observe a strong angular correlation between the two electrons. Classical trajectory Monte Carlo calculations agree quite well with the photoelectron energy distribution that is shifted due to the potential change associated with Auger decay. However, a striking discrepancy results in the distribution of the relative angle between Auger and photoelectron. The classical model predicts a shift in photoelectron flux away from the Auger emission direction, and the data strikingly reveal that the flux is lost rather than diverted, indicating that the two-step interpretation of photoionization followed by Auger emission is insufficient to fully describe the core-photoionization process.

Interference in the collective electron momentum in double photoionization of H2.

We investigate single-photon double ionization of H(2) by 130 to 240 eV circularly polarized photons. We find a double slitlike interference pattern in the sum momentum of both electrons in the molecular frame which survives integration over all other degrees of freedom. The difference momentum and the individual electron momentum distributions do not show such a robust interference pattern. We show that this interference results from a non-Heitler-London fraction of the H(2) ground state where both electrons are at the same atomic center.

Ultrafast probing of core hole localization in N2.

Although valence electrons are clearly delocalized in molecular bonding frameworks, chemists and physicists have long debated the question of whether the core vacancy created in a homonuclear diatomic molecule by absorption of a single x-ray photon is localized on one atom or delocalized over both. We have been able to clarify this question with an experiment that uses Auger electron angular emission patterns from molecular nitrogen after inner-shell ionization as an ultrafast probe of hole localization. The experiment, along with the accompanying theory, shows that observation of symmetry breaking (localization) or preservation (delocalization) depends on how the quantum entangled Bell state created by Auger decay is detected by the measurement.

The simplest double slit: interference and entanglement in double photoionization of H2.

The wave nature of particles is rarely observed, in part because of their very short de Broglie wavelengths in most situations. However, even with wavelengths close to the size of their surroundings, the particles couple to their environment (for example, by gravity, Coulomb interaction, or thermal radiation). These couplings shift the wave phases, often in an uncontrolled way, and the resulting decoherence, or loss of phase integrity, is thought to be a main cause of the transition from quantum to classical behavior. How much interaction is needed to induce this transition? Here we show that a photoelectron and two protons form a minimum particle/slit system and that a single additional electron constitutes a minimum environment. Interference fringes observed in the angular distribution of a single electron are lost through its Coulomb interaction with a second electron, though the correlated momenta of the entangled electron pair continue to exhibit quantum interference.

RT-PCR detection of mRNA recovered from archival glass slide smears.

This manuscript describes a protocol for the utilization of glass slide preparations of hematologic specimens for the recovery of mRNA that is of a quality suitable for the reverse transcription-polymerase chain reaction (RT-PCR) detection of specific gene expression. Total cellular RNA obtained from archival bone marrow aspirate smears of 23 leukemia patients, which had been stored for periods of time from 1 day to 34 mo, were extracted, and 1 to 2 micrograms of each were subjected to RT-PCR using primer pairs specific for the amplification of beta-actin cDNA. Three pairs of primers for the amplification of beta-actin cDNAs of 83,260, and 540 base pairs were used to evaluate the length of mRNA that could be analyzed; the results indicate the consistent amplification of cDNA for the short- and intermediate-sized fragments as revealed by ethidium bromide fluorescence of agarose gel-resolved PCR products. To address the utility of RT-PCR analysis towards the detection of mRNA associated with specific gene alterations in such specimens, a primer pair for amplification of the E2A-PBX1 fusion cDNA was used in PCRs of RT cDNAs for each of the 23 specimens, three of which were pre-B-cell acute lymphoblastic leukemias known to have the t(1;19) karyotype alteration resulting in the fusion of the E2A and PBX1 genes. Agarose gel electrophoresis analysis of the products of these RT-PCR amplifications revealed the amplification of the fusion gene cDNA in only those cases for which there was cytogenetic documentation of t(1;19); these results were confirmed by the Southern filter hybridization of an internal E2A-PBX1 oligonucleotide.(ABSTRACT TRUNCATED AT 250 WORDS)