scholarly journals Evidence for metastable photo-induced superconductivity in K3C60

2021 ◽  
Author(s):  
M. Budden ◽  
T. Gebert ◽  
M. Buzzi ◽  
G. Jotzu ◽  
E. Wang ◽  
...  
Keyword(s):  
Optical Properties ◽  
High Temperature Superconductivity ◽  
Time Windows ◽  
Far Infrared ◽  
Theoretical Description ◽  
Organic Superconductors ◽  
Small Resistance ◽  
Equilibrium Phases ◽  
Short Time ◽  
Non Equilibrium

AbstractExcitation of high-Tc cuprates and certain organic superconductors with intense far-infrared optical pulses has been shown to create non-equilibrium states with optical properties that are consistent with transient high-temperature superconductivity. These non-equilibrium phases have been generated using femtosecond drives, and have been observed to disappear immediately after excitation, which is evidence of states that lack intrinsic rigidity. Here we make use of a new optical device to drive metallic K3C60 with mid-infrared pulses of tunable duration, ranging between one picosecond and one nanosecond. The same superconducting-like optical properties observed over short time windows for femtosecond excitation are shown here to become metastable under sustained optical driving, with lifetimes in excess of ten nanoseconds. Direct electrical probing, which becomes possible at these timescales, yields a vanishingly small resistance with the same relaxation time as that estimated by terahertz conductivity. We provide a theoretical description of the dynamics after excitation, and justify the observed slow relaxation by considering randomization of the order-parameter phase as the rate-limiting process that determines the decay of the light-induced superconductor.

scholarly journals Broadband spectroscopy of astrophysical ice analogues

2019 ◽  
Vol 629 ◽  
pp. A112 ◽  
Author(s):  
B. M. Giuliano ◽  
A. A. Gavdush ◽  
B. Müller ◽  
K. I. Zaytsev ◽  
T. Grassi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Time Domain ◽  
Complex Refractive Index ◽  
Far Infrared ◽  
Infrared Region ◽  
Thz Radiation ◽  
The Real ◽  
Thz Range ◽  
The Time Domain

Context. Reliable, directly measured optical properties of astrophysical ice analogues in the infrared and terahertz (THz) range are missing from the literature. These parameters are of great importance to model the dust continuum radiative transfer in dense and cold regions, where thick ice mantles are present, and are necessary for the interpretation of future observations planned in the far-infrared region. Aims. Coherent THz radiation allows for direct measurement of the complex dielectric function (refractive index) of astrophysically relevant ice species in the THz range. Methods. We recorded the time-domain waveforms and the frequency-domain spectra of reference samples of CO ice, deposited at a temperature of 28.5 K and annealed to 33 K at different thicknesses. We developed a new algorithm to reconstruct the real and imaginary parts of the refractive index from the time-domain THz data. Results. The complex refractive index in the wavelength range 1 mm–150 μm (0.3–2.0 THz) was determined for the studied ice samples, and this index was compared with available data found in the literature. Conclusions. The developed algorithm of reconstructing the real and imaginary parts of the refractive index from the time-domain THz data enables us, for the first time, to determine the optical properties of astrophysical ice analogues without using the Kramers–Kronig relations. The obtained data provide a benchmark to interpret the observational data from current ground-based facilities as well as future space telescope missions, and we used these data to estimate the opacities of the dust grains in presence of CO ice mantles.

Far Infrared Optical Properties of Amorphous As–Se System

1982 ◽  
Vol 21 (Part 1, No. 3) ◽  
pp. 418-423 ◽  
Author(s):  
Seinosuke Onari ◽  
Osamu Sugino ◽  
Michio Kato ◽  
Toshihiro Arai
Keyword(s):  
Optical Properties ◽  
Far Infrared ◽  
Infrared Optical Properties

Optical Properties by Far Infrared Ellipsometry

1968 ◽  
Vol 115 (1) ◽  
pp. 106 ◽  
Author(s):  
Charlie E. Jones ◽  
A. Ray Hilton
Keyword(s):  
Optical Properties ◽  
Far Infrared ◽  
Infrared Ellipsometry

scholarly journals Peripheral Administration of RF9 Does Not Affect Hypothalamic-PituitaryGonadal Axis in Normal Fed Adult Male Macaque

2020 ◽  
pp. 1-5
Author(s):  
Aalia Batool ◽  
Madiha Wazir ◽  
Rahim Ullah ◽  
Aalia Batool ◽  
Rabia Naz ◽  
...  
Keyword(s):  
Adult Male ◽  
Normal Saline ◽  
Time Windows ◽  
Treated Group ◽  
Plasma Testosterone ◽  
Control Group ◽  
Hpg Axis ◽  
Testosterone Levels ◽  
Physiological Conditions ◽  
Short Time

Stress represses hypothalamic-pituitary-gonadal axis (HPG-axis) but RF9, a synthetic peptide, rescues such repression. To assess the role of RF9 in regulating HPG-axis under normal physiological conditions in higher primates, RF9 was administered to intact adult male rhesus monkeys and response of the HPG-axis was examined by measuring plasma testosterone as an end parameter of the axis. Control group (n=4) received normal saline whereas the treated group (n=4) received RF9. On the first day of experiment, four bolus injections of normal saline (1ml/animal) were administered intravenously at 2-hr interval to the control monkeys. Similarly, on the second day of experiment, treated group received four iv bolus injections of RF9 (0.1mg/kg BW) at 2-hr interval. Serial blood samples were collected at 20 min interval during a 6-hr period which started just after first saline/RF9 injection. Plasma testosterone levels were measured by using a specific EIA. Overall means of plasma testosterone levels and plasma testosterone area under curve (AUC) and overall mean testosterone and mean testosterone AUC in short time windows following each injection of RF9 and saline were comparable between the groups. Our results demonstrate that RF9 has no role in regulating HPG-axis under normal physiological conditions in adult male monkeys.

scholarly journals Thermal processes in molecular gas

1991 ◽  
Vol 147 ◽  
pp. 197-204
Author(s):  
J.P. Chièze ◽  
C. de Boisanger
Keyword(s):  
Ultraviolet Radiation ◽  
Molecular Clouds ◽  
Radiation Flux ◽  
Molecular Gas ◽  
Heating And Cooling ◽  
Collective Motions ◽  
Thermochemical Processes ◽  
Order Of Magnitude ◽  
Short Time ◽  
Non Equilibrium

The dynamics of the cold atomic and molecular gas, on which we focus here, is strongly affected by non equilibrium heating and cooling processes. We give two different examples, in which the breaking of the thermal balance is due respectively to variations of the incident ultraviolet radiation flux, and non equilibrium abundances of H2 molecules in molecular clouds envelopes. Fluctuations of the ultraviolet radiation flux in clumpy molecular cloud envelopes result in the formation or the destruction of dense regions. Large density contrasts, greater than one order of magnitude, are easily achieved in cloud regions of moderate visual extinction. Condensation or expansion develop on quite short time scales, of the order of a few tenth of million year, and induce collective motions which can feed turbulence.Another example of the importance of out of equilibrium thermochemical processes is furnished by the study of the H — H2 transition layers in molecular clouds envelopes. They turn out to be unstable against convection-like motions, driven by the energy released by H2 photodestruction. The gas velocities involved in these motions are, again, typical of the observed turbulent velocity in clouds envelopes.

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