Picosecond Optical Second Harmonic Studies of Adsorbate Reduction Kinetics on Cadmium Sulfide

1993 ◽  
Vol 334 ◽  
Author(s):  
T. W. Scott ◽  
J. Martorell ◽  
Y. J. Chang
Keyword(s):  
Cadmium Sulfide ◽  
Near Infrared ◽  
Transient Absorption ◽  
Second Harmonic ◽  
Harmonic Signal ◽  
Recombination Luminescence ◽  
Kinetic Measurements ◽  
Time Resolved ◽  
Sum Frequency ◽  
Kinetics Of

AbstractTime resolved surface second harmonic generation has been used to probe the photoreduction kinetics of malachite green adsorbed onto single crystal cadmium sulfide. A detailed analysis is presented of how the adsorbates and the noncentrosymmetric substrate contribute separately to the total second harmonic signal. Conditions under which the adsorbates can be cleanly detected are described. To complement kinetic measurements of adsorbate reduction, the time evolution of conduction band carriers was determined using sum frequency up conversion of the recombination luminescence. In addition, the formation and decay of surface trapped carriers was monitored using near infrared transient absorption. Comparing the time scale for photoreduction with the relaxation kinetics of mobile and trapped charge carriers indicates that short lived mobile carriers rather than longer lived surface trapped carriers dominate interfacial charge transfer in this system.

scholarly journals Tracking dissociation dynamics of strong-field ionized 1,2-dibromoethane with femtosecond XUV transient absorption spectroscopy

2016 ◽  
Vol 18 (21) ◽  
pp. 14644-14653 ◽  
Author(s):  
Adam S. Chatterley ◽  
Florian Lackner ◽  
Daniel M. Neumark ◽  
Stephen R. Leone ◽  
Oliver Gessner
Keyword(s):  
Absorption Spectroscopy ◽  
Near Infrared ◽  
Transient Absorption ◽  
Extreme Ultraviolet ◽  
Strong Field ◽  
Transient Absorption Spectroscopy ◽  
Time Resolved ◽  
Strong Field Ionization ◽  
Dissociation Dynamics ◽  
Ultraviolet Absorption Spectroscopy

Using femtosecond time-resolved extreme ultraviolet absorption spectroscopy, the dissociation dynamics of the haloalkane 1,2-dibromoethane (DBE) have been explored following strong field ionization by femtosecond near infrared pulses at intensities between 7.5 × 1013 and 2.2 × 1014 W cm−2.

Charge carrier kinetics of carbon nitride colloid: a femtosecond transient absorption spectroscopy study

2016 ◽  
Vol 18 (22) ◽  
pp. 14904-14910 ◽  
Author(s):  
Huiyu Zhang ◽  
Yaping Chen ◽  
Rong Lu ◽  
Ruiyu Li ◽  
Anchi Yu
Keyword(s):  
Charge Carrier ◽  
Carbon Nitride ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Spectroscopy Study ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Femtosecond Transient Absorption ◽  
Femtosecond Transient Absorption Spectroscopy ◽  
Kinetics Of

The charge carrier kinetics of carbon nitride colloid was investigated using a combination of femtosecond transient absorption and picosecond time-resolved fluorescence spectroscopy.

scholarly journals Second-Order Nonlinear Optical Microscopy of a H–Si(111)1 × 1 Surface in Ultra-High Vacuum Conditions

2012 ◽  
Vol 2012 ◽  
pp. 1-14
Author(s):  
Yoshihiro Miyauchi
Keyword(s):  
Delay Time ◽  
Second Harmonic ◽  
High Vacuum ◽  
Life Time ◽  
Hydrogen Desorption ◽  
Ultra High Vacuum ◽  
Pump Light ◽  
Time Resolved ◽  
Sum Frequency ◽  
Intensity Images

This paper reviews the use of optical sum frequency generation (SFG) and second harmonic generation (SHG) microscopy under ultra-high vacuum (UHV) conditions to observe the dynamics of a hydrogen terminated Si(111)1 × 1 surface. First, we took SFG and SHG microscopic images of the surface after IR light pulse irradiation and found that the SHG and nonresonant SFG signals were enhanced, probably due to the formation of dangling bonds after hydrogen desorption. Second, we observed time-resolved SFG intensity images of a H–Si(111)1 × 1 surface. After visible pump light irradiation, the nonresonant SFG signal increased at probe delay time 0 ps and then decreased over a life time of 565 ps. The resonant SFG signal reduced dramatically at 0 ps and then recovered with an anisotropic line shape over a life time of 305 ps. The areas of modulated SFG signals at delay time 277 ps were expanded with an anisotropic aspect. Finally, we observed SFG intensity images of hydrogen deficiency on a Si(111)1 × 1 surface as a function of temperature. These images of the H–Si(111) surface, taken with a spatial resolution of 5 μm at several temperatures from 572 to 744 K, showed that the hydrogen desorbs homogeneously.

scholarly journals NIR-to-NIR Imaging: Extended Excitation Up to 2.2 μm Using Harmonic Nanoparticles with a Tunable hIGh EneRgy (TIGER) Widefield Microscope

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3193
Author(s):  
Laura Vittadello ◽  
Jan Klenen ◽  
Karsten Koempe ◽  
Laura Kocsor ◽  
Zsuzsanna Szaller ◽  
...  
Keyword(s):  
Harmonic Generation ◽  
Near Infrared ◽  
Second Harmonic ◽  
Difference Frequency Generation ◽  
High Energy ◽  
Tissue Imaging ◽  
Sum Frequency ◽  
Nir Imaging ◽  
Deep Tissue Imaging ◽  
Frequency Generation

Near-infrared (NIR) marker-based imaging is of growing importance for deep tissue imaging and is based on a considerable reduction of optical losses at large wavelengths. We aim to extend the range of NIR excitation wavelengths particularly to values beyond 1.6 μm in order to profit from the low loss biological windows NIR-III and NIR-IV. We address this task by studying NIR-excitation to NIR-emission conversion and imaging in the range of 1200 up to 2400 nm at the example of harmonic Mg-doped lithium niobate nanoparticles (i) using a nonlinear diffuse femtosecond-pulse reflectometer and (ii) a Tunable hIGh EneRgy (TIGER) widefield microscope. We successfully demonstrate the existence of appropriate excitation/emission configurations in this spectral region taking harmonic generation into account. Moreover, NIR-imaging using the most striking configurations NIR-III to NIR-I, based on second harmonic generation (SHG), and NIR-IV to NIR-I, based on third harmonic generation (THG), is demonstrated with excitation wavelengths from 1.6–1.8 μm and from 2.1–2.2 μm, respectively. The advantages of the approach and the potential to additionally extend the emission range up to 2400 nm, making use of sum frequency generation (SFG) and difference frequency generation (DFG), are discussed.

scholarly journals Two dimensional diffusion-controlled triplet–triplet annihilation kinetics

2019 ◽  
Vol 10 (32) ◽  
pp. 7633-7640 ◽  
Author(s):  
Grégoire C. Gschwend ◽  
Morgan Kazmierczak ◽  
Astrid J. Olaya ◽  
Pierre-François Brevet ◽  
Hubert H. Girault
Keyword(s):  
Harmonic Generation ◽  
Second Harmonic ◽  
Molecular Crowding ◽  
Two Dimensional ◽  
Time Resolved ◽  
Dimensional Diffusion ◽  
Diffusion Controlled ◽  
Kinetics Of ◽  
Annihilation Reaction ◽  
Triplet Triplet Annihilation

We show with time-resolved second harmonic generation and molecular mechanics simulations that the kinetics of a two-dimensional triplet–triplet annihilation reaction at the liquid–liquid interface is affected by molecular crowding.

scholarly journals Forward and Backward Detectable Gray-Scale Data Storage System in Polymeric Material

2009 ◽  
Vol 2009 ◽  
pp. 1-5
Author(s):  
E. Sungur ◽  
D. Carrara ◽  
G. Taupier ◽  
A. Fort ◽  
L. Mager ◽  
...  
Keyword(s):  
Data Storage ◽  
Azo Dye ◽  
Near Infrared ◽  
Second Harmonic ◽  
Storage System ◽  
Harmonic Signal ◽  
Gray Scale ◽  
Two Photon Microscopy ◽  
Data Storage System ◽  
3D Information

We describe a fast way to encode a gray-scale image with quadratic properties in polymer thin film doped with azo dye. Under a two photon microscopy setup, we induced disorientation in corona-poled azo dye copolymer thin films by a focused near infrared (IR) femtosecond laser beam of variable exposure time. In situ, the sample was then scan to detect the second harmonic signal. We have also tested the backward detection which can provide reading and writing through a single microscope objective. In addition, we were able to store binary 3D information in the bulk of a 50 μm thick film of the same material.

Art is long and time is fleeting: the current problems and future prospects for time-resolved enzyme crystallography

1992 ◽  
Vol 340 (1657) ◽  
pp. 323-334 ◽  
Keyword(s):  
Enzymatic Reaction ◽  
Site Directed Mutagenesis ◽  
Kinetic Measurements ◽  
Laue Diffraction ◽  
Time Resolved ◽  
X Ray Crystallography ◽  
Time Regime ◽  
Kinetics Of ◽  
State Kinetic

I offer comments on the challenges and problems of the future based on the papers in this volume. First, the requirement of the Laue technique for a very well-ordered crystal is a major obstacle to many studies. Efforts to ease this problem are needed. Secondly, the fundamental issues in time-resolved crystallography are now chemical rather than crystallographic. Methods for the rapid initiation of many reactions must be developed. Thirdly, it is imperative that the kinetics of the process in question be studied in the crystal before any diffraction experiments are done. We need better ways to make those solid state kinetic measurements. Fourthly, we should make use of combined methods, such as cryoenzymology plus Laue diffraction or site-directed mutagenesis plus Laue diffraction, to bring many processes into the time regime in which we currently can work. Fifthly, we have to be able to deconvolute diffraction data that come from a mixture of two or three discrete species. Finally, no matter how powerful our synchrotrons get, it seems to me that some of the most important events in any enzymatic reaction are not going to be accessible: consider the formation and decomposition of a transition state as an example. I close by discussing the role of computational biochemistry in filling in those frames of our enzymatic movie that we cannot observe directly by time-resolved X-ray crystallography.

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