1,721,013 research outputs found
FAILURE OF THE LINEAR MIXTURE RULE IN THE VIBRATIONAL-RELAXATION OF CF2HCL IN ARGON
No full textThe vibration to translation (VT) relaxation rates of laser excited CF2HCl + argon mixtures have been measured by means of an interferometric method. Approximately exponential signals have been observed for neat CF2HCl and CF2HCl-rich mixtures, while for Ar-rich mixtures the interferometric signals are clearly non-exponential. For a given Ar fraction the VT rates have been found not to be additive. Deviations from the linear mixture rule are more evident for higher initial vibrational excitations of the relaxing molecules
THE VIBRATIONAL-TRANSLATIONAL RELAXATION OF CF2HCL IN ARGON
No full textWe report in this paper results concerning the vibrational-translational (VT) rates of CF2HCl diluted in Ar as a neutral buffer. The dependence on the buffer concentration and on the initial vibrational energy distribution are obtained by using the 9R(48) and the 9R(34) CO, laser lines for the excitation process. The differences observed between the results corresponding to the two lines bear valuable information about the dependence of the VT relaxation process on the specific initial conditions of vibrational excitation
Generating single attosecond pulse using multi-cycle lasers in a polarization gate
No full textWe analyze the macroscopic effects which are responsible for producing clean isolated pulses lasting few hundreds of attoseconds when starting from multi-cycle fundamental pulses. In particular, we consider
a polarization gating scheme and show that, at high fundamental peak intensities, in the range 0.7-1 PWcm(-2), it usually produces three-four main attosecond pulses of radiation at single dipole level, just located in the leading edge of the laser pulse. We describe the physical mechanisms contributing to the formation of a single attosecond pulse by using a three dimensional non-adiabatic model and a quantum trajectory phase calculation. An analysis of the scheme optimization and stability against various parameters is performed in view of an experimental scheme implementation. (C) 2009 Optical Society of America
Modeling the vibrational relaxation of polyatomic molecules. The methylfluoride case-study
No full textWe present in this paper a theoretical analysis of the vibrational translational (V-T) relaxation process in CH3F, carried out by using a numerical model based on rate equations. In particular, we have analysed the dependence of the V-T relaxation time on the average vibrational energy absorbed per molecule. We have also investigated the influence of the dependence of the rate constants used in the model, on the gas translational temperature. The results of the model clearly outline the strongly nonlinear character of the V-T relaxation process in CH3F, a situation commonly observed in other important polyatomic molecules of intermediate size each as SF6, freons, and related methylhalides
Dynamical medium depletion in high-order above-threshold ionization with few-cycle laser pulses.
No full textPhase-matching effects in the generation of high-energy photons by mid-infrared few-cycle laser pulses
No full textPhase-matching effects in the generatin of high-energy photons by mid-infrared few-cycle laser pulse
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Simultaneous measurements of absorption and vibrational relaxation time in CF2HCl molecules
No full textWe describe in this paper a simple interferometric technique which allows a direct and simultaneous determination of energy absorption and of the vibrational-translational relaxation time of polyatomic molecules strongly excited by reasonant,infrared (10.6 μm) laser radiation. In particular,we have applied this method to the study of freon-22 (CF2HCl),a medium-size molecule that,apart from its potential application in13C isotope separation,shows interesting absorption features in the 10 μm region. The results are also compared with our previous findings in SF6.
Riassunto Si describe in questo lavoro una semplice tecnica interferometrica che permette di misurare contemporaneamente sia l'assorbimento che il tempo di rilassamento vibrazionale-traslazionale di molecole poliatomiche sottoposte ad intensa eccitazione risonante attraverso un laser nell'infrarosso (10.6 μm). In particolare,abbiamo applicato tale tecnica allo studio del freon-22 (CF2HCl),una molecola poliatomica di dimensioni intermedia che,a parte la sua possibile,applicazione nella separazione isotopica del13C,presenta interessanti caratteristiche nell'assorbimento nella regione attorno ai 10 μm. I risultati ottenuti sono discussi e comparati con quelli precedentemente ottenuti sullo SF6
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