نتایج جستجو برای: laser transition

تعداد نتایج: 441155  

In this paper, the magnetic properties of carbon based material, graphene is studied, which is generated by laser ablation in cryogenic media. Transmission electron microscopy (TEM) and alternating gradient force magnetometer (AGFM) are applied to investigate the graphene morphology and magnetic properties, respectively. The graphene synthesized by the laser ablation method exhibits diamagnetic...

بلایت, هری, مختاری, عباس, نئل, جیمز, گهرینک, جیلیان,

Magnetite has a different electrical resistance behavior with temperatures below and above the Verwey temperature. Here, we report on Verwey transition in Fe3O4 by means of the frequency-doubled output from the Ti-sapphire laser in pump-probe experiments and from the insulator to metal transition observed by changing the temperature at the wavelength 370nm (~3.36 eV) both for pump and probe. We...

A. Sh. M. Yassin, M. Zafer, S. Jamal, S. Mohamed,

High quality GGG:Cr,Ca crystal for passive Q-switching Nd:garnet lasers has been grown by the Czochralski method. Thermal treatment of GGG crystals co-doped with Cr4+ and Ca2+ at different temperatures is investigated. The absorption spectra were resolved into different peaks, of modified Gaussian line-shape. Transition from octahedral sites to tetrahedral ones is thermally activated. An...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده علوم 1390

any change in the refractive index of a laser active medium can lead to serious degradation of beam quality, laser beam modes, laser performance and variation in the intensity distribution. alteration in the refractive index of laser active medium is especially notable in high power lasers. it is clear that in the laser beam production, the pumping agent induces a great amount of heat which...

Here, the population transfer between two specific levels of Cesium atomunder the influence of chirped laser source has been numerically investigated. The maingoal of this study is the engineering of the population transfer between the 62S1/2 and 62P1/2levels of Cesium which is corresponding to its D1 transition line using a chirped lasersource. Constructing the system Hamiltonian, as well as t...

Journal: :Optics express 2012
Jianfeng Li Tomonori Hu Stuart D Jackson

A gain-switched laser transition, of a two-laser-transition cascade laser, that is driven by the adjacent laser transition which is Q-switched is demonstrated using a Ho3+-doped fluoride fiber laser. Q-switching the 5I6 → 5I7 transition at 3.002 µm produces stable gain-switched pulses from the 5I7 → 5I8 transition at 2.074 µm; however, Q-switching the 5I7 → 5I8 transition produced multiple gain...

آیت اللهی, سیدمحمدتقی, جمالی, حسین, جهانیان, سارا, روستایی, نرگس, صالحی, مسعود, وهابی, نسیم,

Introduction: Primary angle closure glaucoma suspects is one of the common causes of blindness in the world and methods of treatment are associated with side effects such as loss of corneal endothelial cells. The purpose of this study was to investigate the effects YAG laser peripheral iridotomy on count and morphology of endothelial cells in patients with primary angle closure glaucoma suspect...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد شاهرود - دانشکده پزشکی 1390

nitric oxide (no) is a small molecule synthesized by most of mammalian cells with diverse biological activities including vasodilatation, host defense and wound healing. impaired wound healing is a common occurrence among diabetics and patients receiving glucocorticoid therapy. on the other hand the application of laser in biomedical area have been increased. thus, the current studies were desi...

2012
Y. Wang R. S. Rawat A. Bisht P. Lee U. Ilyas S. V. Springham T. L. Tan

A pre-annealing atmospheric pulsed laser exposure was applied to decrease the phase transition (from chemically disordered A1 phase to chemically ordered L10 phase) temperature of FePt nano-particles on a Si (100) substrate. Different pre-annealing laser energy densities of 0.024 and 0.079 J/cm were utilized to expose the pulsed laser deposition (PLD) FePt thin film samples under atmospheric co...

پایان نامه :دانشگاه آزاد اسلامی واحد علوم پزشکی تهران - دانشکده پزشکی 1390

هدف: این مطالعه به منظور بررسی و مقایسه اثر q-switched nd yag laser و erbium laser در درمان ضایعات پیگمانته انجام شده است. روش مطالعه: 116 فرد مبتلا به ضایعات پیگمانته از نوع فرکل و خال وارد مطالعه شدند که 58 مورد با استفاده از q-switched nd yag laser و 58 مورد با لیزر erbium درمان شدند و در نهایت میزان اثربخشی (از بین رفتن کامل ضایعات) در دو گروه تعیین و مقایسه گردید. یافته ها: در این مطالعه...

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