Femtosecond carrier dynamics in bulk graphite and graphene paper

Femtosecond white-light continuum probe transient absorption and reflectivity measurements of bulk graphite and graphene paper are reported. In graphite, the relaxation of photoinduced electron–hole pairs happens through in-plane electron–electron and electron–phonon scattering in similar, equals200 fs, while the ps dynamics is due to the modulation of the electronic structure by out-of-plane structural motions. The ps dynamics of the optical signal is strongly reduced in graphene paper, where the out-of-plane bond is disrupted, while the short component of the dynamics is identical in both materials. These results show that in 2D-graphene, the carrier relaxation occurs in similar, equals200 fs

RELATIVISTIC JAHN-TELLER EFFECTS IN THE QUARTET STATES OF K3_3 AND RB3_{3}: A VIBRATIONAL ANALYSIS OF THE 24^4E′←^{\prime}\leftarrow{}14^4A2′_2^{\prime} ELECTRONIC TRANSITIONS BASED ON AB INITIO CALCULATIONS

Author Institution: Institute of Experimental Physics, Graz; University of Technology, Petersgasse 16, A-8010 Graz, AustriaWe apply the Multireference Rayleigh Schrodinger Perturbation Theory of second order to obtain the adiabatic potential energy surface of the 1$^4$A$_2^{\prime}$ electronic groundstate and the 2$^4$E$^{\prime}$ excited state of K$_3$ and Rb$_3$. Both trimers show a typical E$\times{}$e Jahn-Teller distortion in their 2$^4$E$^{\prime}$ state, which is analyzed in terms of the relativistic Jahn-Teller effect theory. Linear, quadratic as well as spin-orbit coupling terms are extracted from the \emph{ab initio} results and used to obtain theoretical spectra for a direct comparison to laser-induced fluorescence and magnetic circular dichroism spectra of alkali-doped helium nanodroplets [Aubock et al. J. Chem Phys. \textbf{129} 114501 (2008)]

One- and two-photon spectroscopy of highly excited states of alkali-metal atoms on helium nanodroplets

Alkali-metal atoms captured on the surface of superfluid helium droplets are excited to high energies (approximate to 3 eV) by means of pulsed lasers, and their laser-induced-fluorescence spectra are recorded. We report on the one-photon excitation of the (n+1) p <- ns transition of K, Rb, and Cs (n=4, 5, and 6, respectively) and on the two-photon one-color excitation of the 5d <- 5s transition of Rb. Gated-photon-counting measurements are consistent with the relaxation rates of the bare atoms, hence consistent with the reasonable expectation that atoms quickly desorb from the droplet and droplet-induced relaxation need not be invoked. (C) 2010 American Institute of Physics

Conservation of vibrational coherence in ultrafast electronic relaxation: The case of diplatinum complexes in solution

This work was supported by the Swiss NSF via the NCCR:MUST, contract n° 200021_137717 and IZK0Z2_150425. We thank Yan Choi Lam and Tania Darnton for supplying samples (work at Caltech was supported by NSF CCI Solar FuelsCHE-1305124). Petr Pospíšil (J. Heyrovský Inst.) and Igor Sazanovich (Rutherford Appleton Lab, UK) are thanked for their help with measurements of stationary emission-excitation and nanosecond time-resolved spectra, respectively. We also thank the European collaboration program COST ActionCM1202, the Czech Ministry of Education grant LD14129, and the Czech Science Foundation grant 17-011375 for support

Sprint training in preadolescent soccer players

Young soccer players are usually trained with adult-training methods, even though the physiological adaptations are likely to be very different compared with adults. In contrast, some have suggested training preadolescents only with coordination training. The purpose of this study was to investigate whether coordination or repeatedsprint training better improved speed over 20 m, with and without the ball. Sixteen soccer players (mean age 11 ± 0.5 y) were randomly assigned to a sprint-training group (STG = 7) or a coordination-training group (CTG = 9). The STG trained twice a week for 12 wk and performed 20 repetitions of 20- and 10-m sprints; the CTG performed coordination training (eg, speed ladder running) for the same training duration. Maximal jump height, anthropometric measures, and 20-m sprint time, with and without ball, were evaluated before and after the training period. Statistical significance was determined using two-way ANOVA with repeated measure and Pearson test for correlation. Both groups improved speed without the ball: STG = 3.75 ± 0.10 s to 3.66 ± 0.09 s (P < .05); CTG = 3.64 ± 0.13 s to 3.56 ± 0.13 s (P < .05), with no difference between groups. Sprint time with the ball pre- and posttraining was 4.06 ± 0.11 s and 4.05 ± 0.19 s (P > .05) for STG and 4.04 ± 0.12 s and 3.82 ± 0.15 s (P < .05) for CTG, with a significant difference between groups posttraining (P < .05). There were significant correlations between sprint time without ball, CMJ, and SJ. These data suggest that coordination training increases the speed with the ball more than typical repeated-sprint training. It can be hypothesized that running speed with ball improved more in CTG because this particular action requires improvements in coordination