Theory of heat transfer between adsorbate vibrational degrees of freedom and ultrafast laser heated hot electrons including vibrational intermode coupling is applied to calculate two-pulse correlation, laser fluence dependence and time dependence of lateral hopping of CO molecules from a step to terrace site on a stepped Pt ͑111͒ surface. The intermode coupling is a key ingredient to describe vibrational heating of the frustrated translation mode responsible for the CO hopping. The calculated results are in good agreement with the experimental results, especially if we scale down the experimentally determined absorbed fluence. It is found that CO hopping is induced by indirect heating of the FT mode by the FR mode with a strong frictional coupling to hot electrons.

We study the heat transfer from femtosecond laser-heated hot electrons in a metal to adsorbates in the presence of vibrational-mode coupling. The theory is successfully applied to the experimental result of atomic oxygen hopping on a vicinal Pt͑111͒ surface. The effective friction coupling between hot electrons and the vibrational mode relevant to the hopping motion depends on the transient temperature of the partner mode excited by hot electrons. The calculated two-pulse correlation and fluence dependence of the hopping probability reproduce the experimental results, which were previously analyzed using the hot-electron temperature ͑T e ͒-dependent friction a ͑T e ͒ in a conventional heat transfer equation. A possible elementary process behind such a hypothetic modeling using a ͑T e ͒ is discussed in terms of an indirect heating of the vibrational mode for hopping at the surface. Real-time monitoring of adsorbate motions and of chemical reactions induced by femtosecond pulse laser heating of hot electrons in a metal substrate has been a major goal and challenge in surface reaction dynamics. 1 Recently two different groups carried out time-resolved study of lateral motion of adsorbates on vicinal Pt surfaces using femtosecond laser pulses. 2,3 Employing optical second harmonic generation spectroscopy, Stépán et al. 3 measured the hopping rate of atomic oxygen for step-terrace diffusion on a vicinal Pt͑111͒ surface. The experimental results of the two-pulse correlation ͑2PC͒ and the laser fluence dependence of the hopping probability have been reproduced assuming a hot-electron temperature ͑T e ͒-dependent friction a ͑T e ͒ in the conventional heat transfer equationin order to calculate the transient adsorbate temperature T a ͑t͒. They proposed, as a possible mechanism behind such a hypothetic T e -dependent friction, that it may involve a primary excitation of the O-Pt vibration by hot electrons, which then couples anharmonically to the frustrated translation ͑FT͒ mode of the O atom required to overcome the barrier for lateral motion. This mechanism seems to be supported by several facts. The anharmonic mode coupling in the O-Pt͑111͒ system has been found in the temperature dependence of the vibrational linewidth of the O-Pt stretch mode observed by infrared absorption spectroscopy. 4 Indispensable role of anharmonic mode coupling has also been found in hopping of a single CO on Pd͑110͒ ͑Ref. 5͒ and NH 3 on Cu͑100͒ ͑Ref. 6͒ induced by an inelastic tunneling electron with a scanning tunneling microscope. The T e -dependent friction coupling is also a key ingredient to reproduce the 2PC and the fluence dependence for femtosecond laserinduced desorption of oxygen molecules from a Pd͑111͒ surface. 7 The understanding of the microscopic elementary processes, however, remains at the phenomenological level.No theoretical modeling has been developed to explain why such an anharmonic coupling leads to T e -dependent friction.According to a theory of electronically driven adsorbate excitation, 8 we do not expect T e -depe...

Background and ObjectiveaaThis study evaluated the effects of a mattress with better body pressure dispersal in comparison to a control mattress on sleep quality. MethodsaaIn this randomized crossover study, 10 healthy young men slept in an experimental sleep room on either a functional mattress made from polyurethane, with a special four-layer three-dimensional structure, or a control mattress made from solid polyester wadding, which is a mattress commercially available in Japan. Polysomnography recordings were used to characterize sleep architecture, and the length of slow wave sleep (SWS) episodes and delta power density were calculated from the electroencephalography data and subjective sleep quality was evaluated by questionnaire they answered after waking. ResultsaaThere were no significant differences in sleep latency, the total duration of each sleep stages, total sleep time, or sleep efficiency. Although the difference was subtle, delta power density significantly increased with the functional mattress. There was no difference in the total duration of SWS, but there were significantly fewer SWS episodes with the functional mattress (10.3 ± 1.8) than with the control mattress (16.9 ± 1.2) and longer SWS episode duration (10.9 ± 1.7 min) with the functional mattress than with the control mattress (5.6 ± 0.5 min). ConclusionsaaIt was suggested that the functional mattress lengthened SWS episode duration, and its fragmentation was effective in evaluating the sleep quality of healthy young individuals. Sleep Med Res 2019;10(2):75-82