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101.
Timothy T. Ho Manisha Gupta Fatema Rezwana Chowdhury Zhijiang Chen Ying Yin Tsui 《Applied physics. B, Lasers and optics》2013,113(3):429-436
Here, we report the fabrication of diamond-like carbon (DLC) thin films using pulsed laser deposition (PLD). PLD is a well-established technique for deposition of high-quality DLC thin films. Carbon tape target was ablated using a KrF (248 nm, 25 ns, 20 Hz) excimer laser to deposit DLC films on soap-coated substrates. A laser fluence between 8.5 and 14 J/cm2 and a target to substrate distance of 10 cm was used. These films were then released from substrates to obtain freestanding DLC thin foils. Foil thicknesses from 20 to 200 nm were deposited using this technique to obtain freestanding targets of up to 1-inch square area. Typically, 100-nm-thick freestanding DLC films were characterized using different techniques such as AFM, XPS, and nano-indentation. AFM was used to obtain the film surface roughness of 9 nm rms of the released film. XPS was utilized to obtain 74 % sp2, 23 % sp3, and 3 % C–O bond components. Nano-indentation was used to characterize the film hardness of 10 GPa and Young’s modulus of 110 GPa. Damage threshold properties of the DLC foils were studied (1,064 nm, 6 ns) and found to be 7 × 1010 W/cm2 peak intensity for our best ultrathin DLC foils. 相似文献
102.
Vijaya S. Joshi Sanjoy K. Chowdhury Amitabha Sarkar 《Journal of Chemical Sciences》1995,107(4):447-458
Structural chemistry of organometallic complexes containing pyrazolederived polydentate ligands (without boron) has been reviewed
in the context of current results from this laboratory.
NCL Communication No. 6137 相似文献
103.
Effect of variation of dielectric constant on the magnetic field modulation of exciplex luminescence
The effect of variation of dielectric constant on the relative magnetic field effect in singlet luminescence has been studied
using a typical exciplex system at a saturating field. The study indicates strong specificity in the perturbation of the magnetic
field effect by alcoholic solvents. In contrast to alcohols where relative singlet magnetic field effect is of the order of
2% only, the magnetic field effect in non-alcoholic medium reaches as high as 9%. Moreover, dielectric constant variation
in alcohols yields curves which are distinctly different from those in non-alcoholic media. It turns out that this dependence
of magnetic field effect on dielectric constant is similar in all non-alcoholic solvent mixtures. An analytical study based
on Hong and Noolandi’s solution of Smoluchowski equation has been made. Derived expressions can interpret experimental curves
reasonably well. 相似文献
104.
105.
106.
We present a complete theoretical analysis of the periodic and non-periodic travelling waves in a diatomic chain model, in
the continuum limit by incorporating nonlinear sixth order polarization potential (φ6) at the anion site. We have formulated a nonlinear lattice dynamical theory in which various energy curves are obtained for
different types and magnitudes of the core-shell force constants. For periodic solutions, we have obtained two types of commensurate
wave amplitudes which propagate in the opposite direction with respect to each other. For nonperiodic solutions, we have obtained
various travelling excitations such as kink, antikink, excitons etc. for different values of the mass ratio and velocity parameter.
The dipole moment per unit charge for SrTiO3 has been calculated and it is found that the nonlinear excitations in this model carry large amount of energy as compared
to those obtained from harmonic and anharmonic optical phonons in the φ4-polarizable model. 相似文献
107.
Swapan K. Chowdhury Stephen D. Cameron Donald M. Cox Krzysztof Kniaz Robert A. Strongin Maria A. Cichy John E. Fischer Amos B. Smith 《Journal of mass spectrometry : JMS》1993,28(8):860-866
Electron-capture negative ion chemical ionization (EC-NICI) and field desorption (FD) mass spectrometric techniques were utilized to examine polyfluorinated C60. Two different samples from the same preparation, one prior to sublimation and the other sublimed material, were investigated. From the raw non-sublimed product in EC-NCI six series of ions corresponding to different numbers of attached oxygen atoms were obtained, which are represented by the formula [C60F2nOm]?, where n ranged from 0 to 30 and m from 0 to 5. The sublimed material in EC-NICI produced the same six series of ions with up to 48 fluorine atoms attached to C60. The field desorption of the same sample produced similar results, but the signal-to-noise ratios of the spectra were low. Both samples, in the two different techniques examined, yielded C60F60 ions with only an even number of fluorine atoms attached. The present investigation, for the first time, provides direct experimental evidence for the existence of higher fluorinated C60 up to C60F60 and multiple oxides of polyfluoro-C60 with up to five oxygen atoms attached. 相似文献
108.
We have calculated the phonon and periodon dispersion relations in IV–VI semi-conducting bulk PbTe and SnTe and their superlattice
structure. The model used here is a one-dimensional lattice which includes harmonic interactions up to second neighbours as
well as on-site nonlinear electron-ion interactions at the anion site. We calculate the phonon and periodon dispersion relations
in bulk and PbTe-SnTe superlattice for the transverse optic and acoustic modes using the transfer matrix method. Our analysis
has predicted correct nature of the folding of acoustic and confinement of optical phonons at various frequency intervals
corresponding to pass and stop bands of the superlattices. 相似文献
109.
The elastic scattering of low-energy α-particles by a 4He target has been analysed within the frame-work of a modified Regge-Pole model which reproduces the partial wave phaseshifts in an elegant and simple way and describes all other relevant features of the scattering phenomena. 相似文献
110.
Swapna Roy A. Roy Chowdhury Mrityunjoy De 《International Journal of Theoretical Physics》1988,27(1):47-55
It is demonstrated that Lie point symmetries associated with a nonlinear equation for short waves in three dimensions generate an infinite-dimensional Lie algebra—a loop Algebra. Classification of the independent sets of the subalgebra is done through the adjoint action of the corresponding generators. Different forms of similarity solutions are discussed. 相似文献