Low Frequency, Collective Solvent Dynamics Probed with Time-Resolved THz Spectroscopy

2002 ◽  
pp. 44-57 ◽  
Author(s):  
M. C. Beard ◽  
G. M. Turner ◽  
C. A. Schmuttenmaer
Keyword(s):  
Low Frequency ◽  
Thz Spectroscopy ◽  
Time Resolved ◽  
Solvent Dynamics

scholarly journals Non-equilibrium Phenomena in Superconductors Probed by Femtosecond Time-Domain Spectroscopy

2020 ◽  
Vol 201 (5-6) ◽  
pp. 676-709 ◽  
Author(s):  
J. Demsar
Keyword(s):  
Real Time ◽  
Ultrafast Lasers ◽  
Low Frequency ◽  
Coupling Constants ◽  
Thz Spectroscopy ◽  
Recombination Rates ◽  
Time Resolved ◽  
Time Dynamics ◽  
Open Questions ◽  
Non Equilibrium

AbstractDevelopment of ultrafast lasers and nonlinear optical techniques over the last two decades provides tools to access real-time dynamics of low energy excitations in superconductors. For example, time-resolved THz spectroscopy and time- and angular-resolved photoemission spectroscopy provide access to the real-time dynamics of the superconducting gap amplitude. Such studies enable determination of microscopic parameters like quasi-particle recombination rates, pair-breaking rates and electron–boson coupling constants. Recently, intense THz pulses have been used to probe the nonlinear dynamics, including observation of collective modes. Moreover, using low-frequency electromagnetic pulses, there are several reports of amplification of superconductivity in both conventional and unconventional superconductors. Starting with a brief historical overview of the pioneering work, where non-equilibrium phenomena in superconductors were investigated using quasi-continuous excitation, we review some of the insights that are provided by using real-time approaches. We focus on conventional BCS superconductors, whose ground state is reasonably well understood, and address similarities and open questions related to the corresponding studies in high-$${T}_{c}$$ T c superconductors.

scholarly journals Theta activity paradoxically boosts gamma and ripple frequency sensitivity in prefrontal interneurons

2021 ◽  
Vol 118 (51) ◽  
pp. e2114549118
Author(s):  
Ricardo Martins Merino ◽  
Carolina Leon-Pinzon ◽  
Walter Stühmer ◽  
Martin Möck ◽  
Jochen F. Staiger ◽  
...  
Keyword(s):  
Low Frequency ◽  
Gamma Oscillations ◽  
Brain State ◽  
Gabaergic Interneurons ◽  
Time Resolved ◽  
Cortical Rhythms ◽  
Brain States ◽  
Fast Spiking ◽  
Fast Oscillations ◽  
Cross Frequency Coupling

Fast oscillations in cortical circuits critically depend on GABAergic interneurons. Which interneuron types and populations can drive different cortical rhythms, however, remains unresolved and may depend on brain state. Here, we measured the sensitivity of different GABAergic interneurons in prefrontal cortex under conditions mimicking distinct brain states. While fast-spiking neurons always exhibited a wide bandwidth of around 400 Hz, the response properties of spike-frequency adapting interneurons switched with the background input’s statistics. Slowly fluctuating background activity, as typical for sleep or quiet wakefulness, dramatically boosted the neurons’ sensitivity to gamma and ripple frequencies. We developed a time-resolved dynamic gain analysis and revealed rapid sensitivity modulations that enable neurons to periodically boost gamma oscillations and ripples during specific phases of ongoing low-frequency oscillations. This mechanism predicts these prefrontal interneurons to be exquisitely sensitive to high-frequency ripples, especially during brain states characterized by slow rhythms, and to contribute substantially to theta-gamma cross-frequency coupling.

scholarly journals Monitoring Electron–Phonon Interactions in Lead Halide Perovskites Using Time-Resolved THz Spectroscopy

ACS Nano ◽  
2019 ◽  
Vol 13 (8) ◽  
pp. 8826-8835 ◽  
Author(s):  
Daming Zhao ◽  
Hongwei Hu ◽  
Reinhard Haselsberger ◽  
Rudolph A. Marcus ◽  
Maria-Elisabeth Michel-Beyerle ◽  
...  
Keyword(s):  
Thz Spectroscopy ◽  
Time Resolved ◽  
Halide Perovskites ◽  
Lead Halide
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