Face-centered-cubic Si nanocrystals prepared by microsecond pulsed laser ablation

2007 ◽  
Vol 102 (1) ◽  
pp. 013518 ◽  
Author(s):  
Xi-Wen Du ◽  
Wen-Jing Qin ◽  
Ying-Wei Lu ◽  
Xue Han ◽  
Ying-Song Fu ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Face Centered Cubic ◽  
Si Nanocrystals ◽  
Face Centered

scholarly journals Tailoring Photoluminescence from Si-Based Nanocrystals Prepared by Pulsed Laser Ablation in He-N2 Gas Mixtures

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 440 ◽  
Author(s):  
Anastasiya A. Fronya ◽  
Sergey V. Antonenko ◽  
Alexander Yu. Kharin ◽  
Andrei V. Muratov ◽  
Yury A. Aleschenko ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Near Infrared ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Gas Mixtures ◽  
Si Nanocrystals ◽  
Silicon Target ◽  
Silicon Suboxide ◽  
Pl Emission ◽  
Excitonic States

Using methods of pulsed laser ablation from a silicon target in helium (He)-nitrogen (N2) gas mixtures maintained at reduced pressures (0.5–5 Torr), we fabricated substrate-supported silicon (Si) nanocrystal-based films exhibiting a strong photoluminescence (PL) emission, which depended on the He/N2 ratio. We show that, in the case of ablation in pure He gas, Si nanocrystals exhibit PL bands centered in the “red - near infrared” (maximum at 760 nm) and “green” (centered at 550 nm) spectral regions, which can be attributed to quantum-confined excitonic states in small Si nanocrystals and to local electronic states in amorphous silicon suboxide (a-SiOx) coating, respectively, while the addition of N2 leads to the generation of an intense “green-yellow” PL band centered at 580 nm. The origin of the latter band is attributed to a radiative recombination in amorphous oxynitride (a-SiNxOy) coating of Si nanocrystals. PL transients of Si nanocrystals with SiOx and a-SiNxOy coatings demonstrate nonexponential decays in the micro- and submicrosecond time scales with rates depending on nitrogen content in the mixture. After milling by ultrasound and dispersing in water, Si nanocrystals can be used as efficient non-toxic markers for bioimaging, while the observed spectral tailoring effect makes possible an adjustment of the PL emission of such markers to a concrete bioimaging task.

Structure and magnetic properties of Ni films obtained by pulsed laser ablation deposition

2002 ◽  
Vol 17 (8) ◽  
pp. 2099-2104 ◽  
Author(s):  
J. Vergara ◽  
V. Madurga
Keyword(s):  
Laser Ablation ◽  
Structural Transformation ◽  
Magnetic Moment ◽  
Volume Fraction ◽  
Spontaneous Magnetization ◽  
Hexagonal Phase ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Face Centered Cubic ◽  
Order Of Magnitude

Pulsed laser ablation deposition was used to fabricate Ni films. The structure of the as-deposited films is hexagonal (a = 0.267 nm and c = 0.435 nm), and its resistivity is nearly one order of magnitude larger than the resistivity of bulk Ni. No spontaneous magnetization was observed in the as-deposited samples. Annealing above 200 °C induced an irreversible structural transformation from the metastable hexagonal phase to the stable face-centered-cubic (fcc) one. Parallel to this transformation, the magnetic moment of the annealed Ni samples increased, and their resistivity decreased. On annealing at 440 °C, the structural transformation from the hexagonal-close-packed to the fcc phase was completed, and the magnetic moment, Curie temperature, and electrical resistivity of the fcc Ni films were found similar to the ones observed in bulk Ni. A direct correlation between the volume fraction of the fcc Ni phase in our films and their magnetic moment was established.

scholarly journals Preparation of Au-Ag composite Nanoparticles by Pulsed Laser Ablation in Water for controlling of AIP enzyme Activity in human blood

2019 ◽  
Vol 25 (103) ◽  
pp. 23-36
Author(s):  
Dr. Abdulrahman K. Ali ◽  
Dr. Raad A. Khamis ◽  
Rasha B. Rashid
Keyword(s):  
Laser Ablation ◽  
Human Blood ◽  
Colloidal Suspension ◽  
Pure Water ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Composite Nanoparticles ◽  
Face Centered Cubic ◽  
Optical Extinction ◽  
X Ray

In this work, a colloidal suspension aqueous solution of Au/Ag composite nanoparticles by pulsed laser ablation method was obtained.  Q-switched Nd:YAG, λ=1064nm, 532nm10 ns pulse duration and E=100-900 mJ and by using pure Ag and Au metal plates immersed in  pure water. The optical extinction spectra have been obtained in the Plasmon resonance region. The results are supported by X-ray data and transmission electron microscopy. UV-VIS absorption spectra of produced solution show a sharp peak around 400 nm, 525nm indicating the produced Ag and Au nanoparticles respectively with a narrow size ranging from (5 to 45) nm for Ag NPs, (8-55)nm for Au NPs and (10-170)nm for Au/Ag composite NPs with almost spherical shape X-ray data indicate the  fcc (face-centered cubic) structure.     This work presents the effect of number of pulses on the properties of the prepared Au, Ag and Au-Ag alloy NPs, also included a study of the biomedical effects of Au, Ag, Au-Ag alloy NPs on the activity of Alkaline Phosphatase enzyme in human blood.

Observations on the growth of YBa2Cu3O7-δ thin films on MgO by pulsed-laser ablation

1991 ◽  
Vol 49 ◽  
pp. 1068-1069
Author(s):  
M. Grant Norton ◽  
C. Barry Carter
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Laser Ablation ◽  
Substrate Surface ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Laser Ablation Process ◽  
Deposition Parameters

Pulsed-laser ablation has been widely used to produce high-quality thin films of YBa2Cu3O7-δ on a range of substrate materials. The nonequilibrium nature of the process allows congruent deposition of oxides with complex stoichiometrics. In the high power density regime produced by the UV excimer lasers the ablated species includes a mixture of neutral atoms, molecules and ions. All these species play an important role in thin-film deposition. However, changes in the deposition parameters have been shown to affect the microstructure of thin YBa2Cu3O7-δ films. The formation of metastable configurations is possible because at the low substrate temperatures used, only shortrange rearrangement on the substrate surface can occur. The parameters associated directly with the laser ablation process, those determining the nature of the process, e g. thermal or nonthermal volatilization, have been classified as ‘primary parameters'. Other parameters may also affect the microstructure of the thin film. In this paper, the effects of these ‘secondary parameters' on the microstructure of YBa2Cu3O7-δ films will be discussed. Examples of 'secondary parameters' include the substrate temperature and the oxygen partial pressure during deposition.

scholarly journals Doping nanoparticles using pulsed laser ablation in a liquid containing the doping agent

2019 ◽  
Vol 1 (10) ◽  
pp. 3963-3972 ◽  
Author(s):  
Arsène Chemin ◽  
Julien Lam ◽  
Gaétan Laurens ◽  
Florian Trichard ◽  
Vincent Motto-Ros ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Doping Agent ◽  
Laser Ablation In Liquids ◽  
Dope Nanoparticles

While doping is crucial for numerous technological applications, its control remains difficult especially when the material is reduced down to the nanometric scale. We suggest a new way to dope nanoparticles using laser ablation in liquids.

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