scholarly journals Size dependent efficiency of photophoretic swimmers

2015 ◽  
Vol 184 ◽  
pp. 381-391 ◽  
Author(s):  
Andreas P. Bregulla ◽  
Frank Cichos
Keyword(s):  
Particle Size ◽  
Laser Power ◽  
Symmetry Axis ◽  
Particle Surface ◽  
Finite Size ◽  
Optical Power ◽  
Surface Flow ◽  
Incident Laser ◽  
Size Dependent ◽  
Incident Laser Power

We investigate experimentally the efficiency of self-propelled photophoretic swimmers based on metal-coated polymer particles of different sizes. The metal hemisphere absorbs the incident laser power and converts its energy into heat, which dissipates into the environment. A phoretic surface flow arises from the temperature gradient along the particle surface and drives the particle parallel to its symmetry axis. Scaling the particle size from micro to nanometers, the efficiency of converting optical power into motion is expected to rise with the reciprocal size for ideal swimmers. However, due to the finite size of the metal cap, the efficiency of a real swimmer reveals a maximum depending sensitively on the details of the metal cap shape. We compare the experimental results to numerical simulations.

A Novel Multibranched Chromophore Containing Carbazole Moiety for Two-Photon Microfabrication

2012 ◽  
Vol 485 ◽  
pp. 566-569
Author(s):  
Zhi Yuan Hu ◽  
Fu Quan Guo ◽  
Hao Liang ◽  
Bin Guo
Keyword(s):  
Cross Section ◽  
Laser Power ◽  
Photon Absorption ◽  
Structural Motif ◽  
Incident Laser ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Incident Laser Power ◽  
Potential Applications ◽  
Pentaerythritol Triacrylate

A novel multibranched chromophore containing carbazole moiety，4, 4´, 4´´-tris(9-carbazyl-trans-styryl) triphenylamine (TCSTPA)，was synthesized and characterized by 1HNMR and elemental analysis. A larger two-photon absorption (TPA) cross section of the chromophore was obtained as high as 2350 GM compared to that of the traditional linear chromophore when pumped by a femtosecond laser at 800 nm. Microstructure based on TPA induced polymerization with a spatial resolution of submicron was fabricated under much lower incident laser power using TCSTPA as a TPA photoinitiator and a multifunctional resin of pentaerythritol triacrylate (PETA) as a polymerizable monomer. The result indicates potential applications of this kind of chromophores with multibranched structural motif in the fabrication of polymer and functional microdevices.

scholarly journals Photostability of Uranine via Crossed-Beam Thermal Lens Technique

2007 ◽  
Vol 2007 ◽  
pp. 1-5
Author(s):  
M. Zein El-Din ◽  
K. Elsayed ◽  
S. M. Al-Sherbini ◽  
M. A. Harith
Keyword(s):  
Thermal Lens ◽  
Laser Power ◽  
Modulation Frequency ◽  
Wavelength Modulation ◽  
Incident Laser ◽  
Diagnostic Aid ◽  
Sample Concentration ◽  
Incident Laser Power ◽  
Experimental Parameters ◽  
Photochemical Quantum Yield

Uranine is a diagnostic aid in ophthalmology and is used as an immunohistological stain. A photostability study on this important compound using a crossed-beam thermal lens (TL) technique was carried out. The study is based on the photodegradation (PD) behavior and rate regarding some experimental parameters such as the incident laser power, wavelength, modulation frequency, and sample concentration. The effects of such parameters on the TL signal and PD rate are discussed in details. It has been found that the PD rate is proportional to the power of the pumping laser and the concentration of the sample within the investigated range. However, the modulation frequency is found not to influence the PD rate. The photochemical quantum yield has been measured using potassium ferrioxalate actinometry and it was found to be very low.

Effect of incident laser power and incorporating polariton effects in GaN microrods

2019 ◽  
Vol 209 ◽  
pp. 328-332
Author(s):  
Poulami Ghosh ◽  
Dapeng Yu ◽  
Mingyuan Huang
Keyword(s):  
Laser Power ◽  
Incident Laser ◽  
Incident Laser Power

Nonlinear transmittance and optical power limiting in magnesium ferrite nanoparticles: effects of laser pulsewidth and particle size

RSC Advances ◽  
2016 ◽  
Vol 6 (108) ◽  
pp. 106754-106761 ◽  
Author(s):  
Sreekanth Perumbilavil ◽  
Kishore Sridharan ◽  
Ann Rose Abraham ◽  
Harsha P. Janardhanan ◽  
Nandakumar Kalarikkal ◽  
...  
Keyword(s):  
Particle Size ◽  
Femtosecond Laser ◽  
Optical Power ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Ferrite Nanoparticles ◽  
Magnesium Ferrite ◽  
Nonlinear Transmission ◽  
Size Dependent ◽  
Optical Power Limiting

We report comparative measurements of size dependent nonlinear transmission and optical power limiting in nanocrystalline magnesium ferrite (MgFe2O4) particles excited by short (nanosecond) and ultrashort (femtosecond) laser pulses.

scholarly journals Plasmon-driven surface catalytic reaction of 4-ethynylaniline in a liquid environment

RSC Advances ◽  
2018 ◽  
Vol 8 (37) ◽  
pp. 20499-20504
Author(s):  
Yu Liu ◽  
Caiqing Ma ◽  
Yanqiu Yang ◽  
Yuanchun Zhao ◽  
Shiwei Wu ◽  
...  
Keyword(s):  
Exposure Time ◽  
Catalytic Reaction ◽  
Laser Power ◽  
Incident Laser ◽  
Interesting Phenomenon ◽  
Liquid Environment ◽  
Incident Laser Power ◽  
Raman Intensities

The mechanism of Ag NP induced dimerization of PEAN was investigated by using SERS spectra. A very interesting phenomenon was discovered, that is where the relative Raman intensities of b2 modes increased either with increasing incident laser power or exposure time.

scholarly journals Demonstration of temperature-plateau superheated liquid by photothermal conversion of plasmonic titanium nitride nanostructures

Nanoscale ◽  
2018 ◽  
Vol 10 (39) ◽  
pp. 18451-18456 ◽  
Author(s):  
Satoshi Ishii ◽  
Ryosuke Kamakura ◽  
Hiroyuki Sakamoto ◽  
Thang D. Dao ◽  
Satish L. Shinde ◽  
...  
Keyword(s):  
Titanium Nitride ◽  
Laser Power ◽  
Superheated Liquid ◽  
Liquid Temperature ◽  
Incident Laser ◽  
Photothermal Conversion ◽  
Incident Laser Power ◽  
Conductive Substrate ◽  
Temperature Plateau

When photothermally superheated liquid is on a high thermal conductive substrate, the liquid temperature stays constant for a certain range of incident laser power before bubbles are formed.

Self-Focusing of Laser Light and Stimulated Scattering Processes in Transparent and Absorbing Liquids: 1. Self-Focusing

1970 ◽  
Vol 25 (12) ◽  
pp. 1868-1879 ◽  
Author(s):  
M. Maier ◽  
O. Rahn ◽  
G. Wendl
Keyword(s):  
Laser Power ◽  
Laser Light ◽  
Beam Diameter ◽  
Incident Laser ◽  
Stimulated Scattering ◽  
Light Pulses ◽  
Incident Laser Power ◽  
Self Focusing ◽  
Stimulated Brillouin ◽  
Good Agreement

Abstract The spatial and temporal development of self-focusing of light pulses is investigated. The beam diameter in CS2 and molten para-di-chlorobenzene decreases with increasing incident laser power to small values in good agreement with theory. The strong influence of beam divergence, non-linearity of refractive index, and absorption on self-focusing action is found to agree well with numerical calculations. It is shown that both backward stimulated Brillouin and Raman scattering terminate the self-focusing process.

scholarly journals Graphitisation of Waste Carbon Powder with Femtosecond Laser Annealing

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 120
Author(s):  
Lucas Lum ◽  
Chong Wei Tan ◽  
Chun Fei Siah ◽  
Kun Liang ◽  
Beng Kang Tay
Keyword(s):  
Electrical Conductivity ◽  
Femtosecond Laser ◽  
Laser Power ◽  
Laser Annealing ◽  
Structural Characteristics ◽  
Carbon Powder ◽  
Incident Laser ◽  
Destructive Effect ◽  
Incident Laser Power ◽  
Post Process

Graphitisation of structural characteristics and improvement in electrical conductivity was reported onto waste carbon powder through femtosecond laser annealing. Raman spectroscopy on the carbon powder pre- and post-annealing showed a shift from amorphous-like carbon to graphitic-like carbon, which can be explained by the three-stage model. Electrical I-V probing of the samples revealed an increase in conductivity by up to 90%. An increase in incident laser power was found to be correlated to an increase in conductivity. An average incident laser power of 0.104 W or less showed little to no change in electrical characteristics, while an average incident laser power of greater than 1.626 W had a destructive effect on the carbon powder, shown through the reduction in powder. The most significant improvement in electrical conductivity has been observed at laser powers ranging from 0.526 to 1.286 W. To conclude, the graphitisation of waste carbon powder is possible using post-process femtosecond laser annealing to alter its electrical conductivity for future applications.

A tunable positive and negative photoconductive photodetector based on a gold/graphene/p-type silicon heterojunction

2019 ◽  
Vol 7 (4) ◽  
pp. 887-896 ◽  
Author(s):  
Peng-Fei Wang ◽  
Yu Liu ◽  
Jun Yin ◽  
Wanyun Ma ◽  
Zhanmin Dong ◽  
...  
Keyword(s):  
Laser Power ◽  
Incident Laser ◽  
Fast Switching ◽  
Type Silicon ◽  
Incident Laser Power ◽  
P Type ◽  
Power Densities

Fast switching of positive and negative photocurrents of a device under the modulation of different incident laser power densities.

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