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The magnetic hyperfine structure of certain low-JQ lines in the optical spectrum of NbO shows an unusual intensity cancellation effect. In contrast to the normal pattern that ΔF=ΔJ hyperfine components are the strongest, the intensities of the ΔF=ΔJ components are found to pass through zero near the center of the range of F values. Although this effect is implicit in the intensity formulas for the quadrupole hyperfine structure of microwave lines, it seems not to have been noted in published spectra because of the unusual circumstances required for its appearance: a nuclear spin of at least I=5/2 is needed, and only Q lines show it. A classical vector model is presented for its interpretation. [ABSTRACT FROM AUTHOR]

The (0,0) band of the B 4Π–X 4Σ- transition of NbO, near 6600 Å, has been analyzed from spectra taken at sub-Doppler resolution. The transition is notable for the great width of its Nb nuclear hyperfine structure, which is caused principally by the unpaired 5sσ electron in the ground state interacting with the large magnetic moment of the 4193Nb nucleus (I=9/2). A fit to the ground-state combination differences, including four very precise microwave lines measured by Suenram et al. [J. Mol. Spectrosc. 148, 114 (1991)], has given a comprehensive set of rotational, spin, and hyperfine parameters. Prominent among these are the third-order spin–orbit distortions of the spin-rotation interaction and the Fermi contact interaction, which are large and well determined, reflecting different degrees of spin–orbit contamination of the the 4Σ1/2- and 4Σ3/2- components of the ground state.The δ 2π B 4Π state was hard to fit, for a number of reasons. First, its spin–orbit structure is asymmetric, because of strong perturbations by a 2Π state which has been identified in this work, from among the various weak bands in the NbO spectrum near 7000 Å; the result is that many high order centrifugal distortion terms are needed in an effective Hamiltonian model for the rotation. Second, the hyperfine structure is perturbed, not only by this 2Π state, but by distant Σ and Δ states at higher energy. The δ 2σ* C 4Σ- state at 21 350 cm-1 appears to be one of these. The distant states generate large apparent nuclear spin-rotation interactions, both within and between the Λ components of the Π state, as a result of cross terms between matrix elements of the operators -2BJ·L and aI·L. Similar cross terms arising from the operators AL·S and aI·L produce corrections to the Fermi contact matrix elements and are responsible for the unexpected... [ABSTRACT FROM AUTHOR]

The microwave pure rotational transitions J=3/2←1/2 and 5/2←3/2 have been measured for gas phase CuO in its X 2Π state, using microwave-optical double resonance. The copper hyperfine structure was observed, and has been analyzed for the first time for the ground state of an orbitally degenerate transition metal-containing molecule in the gas phase. Rotational, lambda-doubling, and magnetic and electric hyperfine parameters have been evaluated; the Fermi contact parameter bF has been found to be very large and negative. The problem of determining the signs of the ‘‘off-diagonal’’ hyperfine parameters in 2Π electronic states is discussed. [ABSTRACT FROM AUTHOR]

Representational co-speech gestures are generally assumed to be increasingly produced in more difficult compared with easier verbal tasks, as maintained by theories suggesting that gestures arise from processing difficulties during speech production. However, the gestures-as-simulated-action framework proposes that more representational gestures are produced with stronger rather than weaker mental representations that are activated in terms of mental simulation in the embodied cognition framework. We tested these two conflicting assumptions by examining verbal route descriptions that were accompanied by spontaneous directional gestures. Easy descriptions with strong activation were accompanied more often by gestures than difficult descriptions with weak activation. Furthermore, only gesture-speech matches-but not gesture-picture matches-were increasingly produced with difficult lateral directions compared with easy nonlateral directions. We argue that lateral gesture-speech matches underlie stronger activated mental representations in mental imagery. Thus, all results are in line with the gestures-as-simulated-action framework and provide evidence against the view that gestures result from processing difficulties., (Copyright © 2010 Cognitive Science Society, Inc.)

We report the direct observation of interference effects in a Young's double-slit experiment where the interfering waves are two spatially separated components of the de Broglie wave of single 1.3 MeV hydrogen atoms formed close to either target nucleus in H++H2 electron-transfer collisions. Quantum interference strongly influences the results even though the hydrogen atoms have a de Broglie wavelength, lambda_{dB}, as small as 25 fm.