Photoionization Yields in Intense fs-Laser Fields – A Systematic Investigation of Chirp Effects

2015 ◽  
Vol 229 (10-12) ◽  
Author(s):  
Nicola Reusch ◽  
Steffen Griebe ◽  
Johannes Karges ◽  
Karl-Michael Weitzel
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Systematic Investigation ◽  
Spectral Phase ◽  
Second Order ◽  
Laser Ionization ◽  
Laser Fields ◽  
Linear Chirp ◽  
Fs Laser ◽  
Hydrocarbon Molecules

AbstractThe femtosecond laser ionization of several small hydrocarbon molecules (methane, ethane, propane) has been investigated as a function of the second order spectral phase (linear chirp) of laser pulses centered at

Fabrication and Characterization of Si Nano-Columns by Femtosecond Laser

2012 ◽  
Vol 16 ◽  
pp. 15-20 ◽  
Author(s):  
Omid Tayefeh Ghalehbeygi ◽  
Vural Kara ◽  
Levent Trabzon ◽  
Selcuk Akturk ◽  
Huseyin Kizil
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Laser Beam ◽  
Chemical Etching ◽  
Silicon Surface ◽  
Laser Pulses ◽  
Laser Beam Profile ◽  
Fs Laser ◽  
Fabrication And Characterization

We fabricated Si Nano-columns by a femtosecond laser with various wavelengths and process parameters, whilst the specimen was submerged in water. The experiments were carried out by three types of wavelengths i.e. 1030 nm, 515nm, 343nm, with 500 fs laser pulses. The scales of these spikes are much smaller than micro spikes that are constructed by laser irradiation of silicon surface in vacuum or gases like SF6, Cl2. The Si nano-columns of 300 nm or less in width were characterized by SEM measurements. The formation of these Si Nano-columns that were revealed by SEM observation, indicates chemical etching with laser ablation occurred when surface exposed by laser beam. We observed 200 nm spikes height at the center of laser beam profile and the ones uniform in height at lateral incident area.

scholarly journals Nonperturbative generation of above-threshold harmonics from pre-excited argon atoms in intense mid-infrared laser fields

2017 ◽  
Vol 5 ◽  
Author(s):  
Guihua Li ◽  
Hongqiang Xie ◽  
Ziting Li ◽  
Jinping Yao ◽  
Wei Chu ◽  
...  
Keyword(s):  
Excited State ◽  
Femtosecond Laser ◽  
Pulse Energy ◽  
Laser Pulses ◽  
Infrared Laser ◽  
Femtosecond Laser Pulses ◽  
Probe Laser ◽  
Laser Fields ◽  
Mid Infrared ◽  
Highly Nonlinear

We experimentally investigate the generation of above-threshold harmonics completely from argon atoms on an excited state using mid-infrared femtosecond laser pulses. The highly nonlinear dependences of the observed signal on the pulse energy and polarization of the probe laser pulses indicate its nonperturbative characteristic.

A STUDY OF FEMTOSECOND LASER POLISHING OF CVD NANOPOLYCRYSTALLINE DIAMOND FILMS

2021 ◽  
pp. 2150023
Author(s):  
YU-XIAO CUI ◽  
PING GUO ◽  
XUEMING ZHU ◽  
YAN-LING TIAN ◽  
DA-WEI ZHANG ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Fluence ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Laser Pulses ◽  
Promising Technique ◽  
Laser Polishing ◽  
Laser Fluences ◽  
Fs Laser ◽  
The Mean

Femtosecond (fs) laser ablation has been recognized as an effective and promising technique for high-precision processing of natural and synthesized diamond. In this work, a study of femtosecond laser polishing for nanopolycrystalline diamond (NCD) films by chemical vapor deposition (CVD) is reported. The laser irradiation is induced by 200-fs laser pulses with a repetition frequency of 50[Formula: see text]MHz, and various laser fluences are employed to investigate their polishing effectiveness. The results show that the optimal laser fluence is 0.7[Formula: see text]J/cm2, at which the nanodiamond grains on top of the cauliflower-like clusters of NCD films can be ablated. With such laser fluence, the mean surface roughness of NCD films reduces from 73.84[Formula: see text]nm to 31.88[Formula: see text]nm, which presents a 57% reduction. Nevertheless, when the laser fluence rises beyond 0.7[Formula: see text]J/cm2, large amount of amorphous carbon (a-C) balls and porous lava-like morphology would come into being, resulting in severe degradation of the NCD surface.

scholarly journals Distinction of Structural Isomers of Benzenediamin and Difluorobenzene by Means of Chirped Femtosecond Laser Ionization Mass Spectrometry

2018 ◽  
Vol 232 (5-6) ◽  
pp. 689-703 ◽  
Author(s):  
Nicola Reusch ◽  
Viola Krein ◽  
Nikolaus Wollscheid ◽  
Karl-Michael Weitzel
Keyword(s):  
Mass Spectrometry ◽  
Femtosecond Laser ◽  
Chromatographic Method ◽  
Ionization Mass ◽  
Laser Ionization ◽  
Structural Isomers ◽  
Analytical Technique ◽  
Flight Mass Spectrometry ◽  
Alternative Approach ◽  
Fs Laser

Abstract Structural isomers of disubstituted benzenes are difficult to distinguish with most mass spectrometric methods. Consequently, conventional concepts for the distinction of isomers are based on coupling mass spectrometry with a chromatographic method. As an alternative approach, we propose the combination of femtosecond laser ionization with time-of-flight mass spectrometry (fs-LIMS). The possibility of systematic tailoring of fs-laser pulse shapes opens access to a multidimensional analytical technique capable of distinguishing structural isomers of the title molecules.

Modifying the second order dispersion of femtosecond laser pulses to crack silver nanoparticles and control their dimensions

2019 ◽  
Vol 118 ◽  
pp. 1-7
Author(s):  
Thiago da S. Cordeiro ◽  
Marcello M. Amaral ◽  
Ricardo A. de Matos ◽  
Flávia R.O. Silva ◽  
Nilson D. Vieira Junior ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Second Order ◽  
And Control ◽  
Order Dispersion

Revealing silent vibration modes of nanomaterials by detecting anti-Stokes hyper-Raman scattering with femtosecond laser pulses

Nanoscale ◽  
2016 ◽  
Vol 8 (3) ◽  
pp. 1572-1579 ◽  
Author(s):  
Jianhua Zeng ◽  
Lei Chen ◽  
Qiaofeng Dai ◽  
Sheng Lan ◽  
Shaolong Tie
Keyword(s):  
Femtosecond Laser ◽  
Raman Scattering ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Second Order ◽  
Vibration Modes ◽  
Anti Stokes

A strong anti-Stokes hyper-Raman scattering was observed in nanomaterials with large second-order susceptibilities by using femtosecond laser pulses and many Raman inactive vibration modes were clearly revealed.

Formation of Silicon and Silicon-Based Semiconductor Materials via Photoinduced Reaction Using Femtosecond Laser

2011 ◽  
Vol 1288 ◽  
Author(s):  
Masakazu Nishimura ◽  
Shingo Kanehira ◽  
Masaaki Sakakura ◽  
Yasuhiko Shimotsuma ◽  
Kiyotaka Miura ◽  
...  
Keyword(s):  
Particle Size ◽  
Phase Transformation ◽  
Femtosecond Laser ◽  
Laser Irradiation ◽  
Sandwich Structure ◽  
Laser Pulses ◽  
Semiconductor Materials ◽  
Photoinduced Reaction ◽  
Fs Laser ◽  
Silicon Based

ABSTRACTWe have succeeded in silicon (Si) precipitation inside a glass/aluminum (Al) sandwich structure via photoinduced reaction using femtosecond (fs) laser irradiation. The sandwich structure was fabricated by direct bonding below 573 K. Raman spectra at the photomodified area indicated that Si crystals formed at the interface between the glass and metallic Al after the laser irradiation. In addition, the particle size of the precipitated Si could be changed by changing the pulse energy of the laser. Furthermore, we have also focused the laser pulses on Fe-Si film to trigger crystallization and phase transformation of FexSiy at the interface between Fe/Si multilayer and glass.

scholarly journals Generation of elliptically polarized nitrogen ion laser fields using two-color femtosecond laser pulses

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Ziting Li ◽  
Bin Zeng ◽  
Wei Chu ◽  
Hongqiang Xie ◽  
Jinping Yao ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Laser Fields ◽  
Ion Laser ◽  
Nitrogen Ion ◽  
Elliptically Polarized
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