Subpicosecond laser spectroscopy: strong field effects on molecular photophysics and dynamics

1983 ◽  
Vol 61 (5) ◽  
pp. 975-982 ◽  
Author(s):  
E. Quitevis ◽  
P. M. Kroger ◽  
C. Kalpouzos ◽  
G. A. Kenney-Wallace
Keyword(s):  
Strong Field ◽  
Single Pulse ◽  
Field Effects ◽  
Laser Pumping ◽  
Dense Media ◽  
Polyatomic Systems ◽  
Reorientational Dynamics ◽  
Argon Ion ◽  
Liquid Chlorobenzene

The possible role of strong field effects is discussed in the context of picosecond relaxation and reaction in polyatomic systems. The picosecond pulse diagnostics from an argon-ion synchronously pumped dye laser are then outlined in terms of cavity detuning and laser pumping parameters. A profile of auto-correlation data on ensemble-averaged pulses and streak camera data on single pulses is presented, from which the domain of stable, single pulse operation can be deduced. Finally data are presented on the photoionization and energy relaxation of pyrene in alcohols and micelles, and for the reorientational dynamics of liquid chlorobenzene, which illustrate different consequences of strong field phenomena in dense media.

scholarly journals The role of electric field, peripheral chains, and magnetic effects on significant 1H upfield shifts of the encapsulated molecules in chalcogen-bonded capsules

2021 ◽  
Vol 23 (35) ◽  
pp. 19647-19658
Author(s):  
Demeter Tzeli ◽  
Ioannis D. Petsalakis ◽  
Giannoula Theodorakopoulos ◽  
Faiz-Ur Rahman ◽  
Yang Yu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Chemical Shifts ◽  
Electric Field Effects ◽  
Magnetic Effects ◽  
Field Effects ◽  
Equal Importance

Significant 1H upfield chemical shifts of the guests in the capsules are consequences of polarizability of chalcogens, electric field effects and peripheral chains. The effects of the electric field and of magnetic field are of equal importance.

Electric Field Effects on Guinea Pig Serum: The Role of Free Radicals

2007 ◽  
Vol 26 (3) ◽  
pp. 207-223 ◽  
Author(s):  
Göknur Güler ◽  
Zerrin Türközer ◽  
Nesrin Seyhan
Keyword(s):  
Free Radicals ◽  
Guinea Pig ◽  
Electric Field ◽  
Electric Field Effects ◽  
Field Effects ◽  
Pig Serum

scholarly journals Corticospinal excitability underlying digit force planning for grasping in humans

2014 ◽  
Vol 111 (12) ◽  
pp. 2560-2569 ◽  
Author(s):  
Pranav Parikh ◽  
Marco Davare ◽  
Patrick McGurrin ◽  
Marco Santello
Keyword(s):  
Primary Motor Cortex ◽  
Single Pulse ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Reach To Grasp ◽  
Grasp Planning ◽  
Sensorimotor Memory ◽  
Force Planning ◽  
Intracortical Inhibition And Facilitation

Control of digit forces for grasping relies on sensorimotor memory gained from prior experience with the same or similar objects and on online sensory feedback. However, little is known about neural mechanisms underlying digit force planning. We addressed this question by quantifying the temporal evolution of corticospinal excitability (CSE) using single-pulse transcranial magnetic stimulation (TMS) during two reach-to-grasp tasks. These tasks differed in terms of the magnitude of force exerted on the same points on the object to isolate digit force planning from reach and grasp planning. We also addressed the role of intracortical circuitry within primary motor cortex (M1) by quantifying the balance between short intracortical inhibition and facilitation using paired-pulse TMS on the same tasks. Eighteen right-handed subjects were visually cued to plan digit placement at predetermined locations on the object and subsequently to exert either negligible force (“low-force” task, LF) or 10% of their maximum pinch force (“high-force” task, HF) on the object. We found that the HF task elicited significantly smaller CSE than the LF task, but only when the TMS pulse coincided with the signal to initiate the reach. This force planning-related CSE modulation was specific to the muscles involved in the performance of both tasks. Interestingly, digit force planning did not result in modulation of M1 intracortical inhibitory and facilitatory circuitry. Our findings suggest that planning of digit forces reflected by CSE modulation starts well before object contact and appears to be driven by inputs from frontoparietal areas other than M1.

scholarly journals Спектральное исследование фотодинамических процессов в системе C-=SUB=-60-=/SUB=--(н-метилпирролидон)-кислород

2021 ◽  
Vol 129 (12) ◽  
pp. 1493
Author(s):  
И.М. Кисляков ◽  
И.М. Белоусова ◽  
В.М. Киселев ◽  
И.В. Багров ◽  
А.М. Стародубцев ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Singlet Oxygen ◽  
Transient Absorption ◽  
Rapid Quenching ◽  
Quenching Rate ◽  
Broadband Absorption ◽  
Laser Pumping ◽  
Time Dependencies ◽  
Quenching Rate Constant

The processes of photoexcitation and energy transfer in an air-saturated solution of fullerene C60 in n-methylpyrrolidone are studied. With femtosecond laser pumping at a wavelength л(p) = 520 nm, transient absorption spectra were obtained in the range 470-750 nm. Broadband absorption is observed at л > 650 nm as a result of aggregation of fullerene molecules, characterized by a short decay time of the picosecond scale. The analysis of the time dependencies indicates the presence of several processes. Within the proposed interpretation, we state a remarkable reduction in the time of singlet-triplet intersystem crossing with an increase of nanocluster size while the rapid quenching of the singlet state varies only slightly. The quantum yield of the triplet state can therefore increase, reaching 0.14. The phosphorescence spectra of singlet oxygen with a maximum at л = 1276 nm were measured with LED excitation at various wavelengths in the range 370-625 nm. The lifetime and quenching rate constant of singlet oxygen in n-methylpyrrolidone are determined. The combined quantum yield of triplet fullerene and singlet oxygen in n-methylpyrrolidone is estimated as 0.74. The efficiency spectra of the singlet oxygen photosensibilization in the C60-(n-methylpyrrolidone)-oxygen system are obtained, indicating the increasing role of large nanoclusters in this process during aging of the solution.

Strong-field effects in coherent saturation spectroscopy of atomic beams

1994 ◽  
Vol 49 (6) ◽  
pp. 4794-4825 ◽  
Author(s):  
J. Ishikawa ◽  
F. Riehle ◽  
J. Helmcke ◽  
Ch. J. Bordé
Keyword(s):  
Strong Field ◽  
Saturation Spectroscopy ◽  
Field Effects ◽  
Atomic Beams
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