Tumoricidal effects of nanomaterials in HeLa cell line

Laser Physics - The current study exhibits the cellular response of HeLa (cervical cancer) cells to metal oxides ultrafine nanomaterials e.g. manganese dioxide nanowires (MnO2 NRs), iron oxide...     

Natural line shape

The observable line shape of the spontaneous emission depends on the procedure of atom’s excitation. The spectrum of radiation emitted by a two-level atom excited from the ground state by a π pulse of the resonant pump field is calculated for the case when the Rabi frequency is much larger than the relaxation rate. It is shown that the central part of the spectral distribution has a standard Lorentzian form, whereas for detunings from the resonance that are larger than the Rabi frequency the spectral density falls off faster. The shape of the wings of the spectral line is sensitive to the form of the π pulse. The implications for the quantum Zeno effect theory and for the estimates of the duration of quantum jumps are discussed. The article is published in the original.     

On the line shape of EELS-spectra

The influence of anharmonic coupling between vibrations of an adsorbate parallel and perpendicular to the surface on electron energy loss spectra is investigated. Although in most cases vibrations parallel to the surface are not directly observable in EELS, this anharmonic coupling can be the origin of satellites in the loss spectra.     

On the spin-flip line shape in CdS

The longitudinal relaxation time of Spin-Flip Raman scattering (SFRS) in n-CdS is explained in terms of the Elliott mechanism. The energy dispersion of spectroscopic factors of the conduction electrons and the Hasegawa model yield a transversal relaxation time different from the longitudinal relaxation time, but do not reproduce the experimental value. The diffusion coefficient, responsible for the SFRS line width behavior with temperature in n-CdS, is explained based upon hopping effects in the low temperature region.     

Magnetic resonance line shape

The long-time asymptote of the magnetization correlation function and its distribution are investigated with slow motion of the spin and molecular subsystem taken into account the most. The influence of molecular drift in the field of the thermal hydrodynamic fluctuations on the magnetic resonance line shape is examined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 118–121, May, 1976.     

Basics of NMR line shape in quasicrystals

The measurement and analysis of broad nuclear magnetic resonance (NMR) spectra of quasicrystals require experimental methods and theoretical interpretations different from NMR investigations of regular periodic crystals. Frequency- and field-sweep methods for recording quasicrystalline NMR spectra are described and compared with the measurement of²⁷Al NMR spectra of icosahedral AlPdMn and decagonal AlNiCo quasicrystals. The nuclear spin interactions that determine the NMR line shape are the same for both types of the above Al-based quasicrystals, where the electric quadrupolar interaction with the broad distribution of its electric field gradient parameters predominantly determines the shape of the broad satellite “background” intensity. The essential observations are an almost isotropic²⁷Al NMR spectrum of the icosahedral quasicrystals and a strong angular dependence of the spectrum of decagonal quasicrystals.     

On calculation of the molecular line shape in the wings

The general formulation of the molecular spectral line shapes is treated in a consistent way in the two limiting regions of the core and wings of a line. We have extended the scope of the quasistatic theory of Margenau by explicitly introducing, for an anisotropic interaction, the influence of the non-resonant character of the exchange of quanta between the active molecule and its surroundings, which is of particular importance for molecular collisions. The present development is restricted to the two first orders with respect to the perturbing potential and includes a convenient cutoff procedure. It is shown that, for the exactly resonant limit, we obtain the exact frequency dependence with an error less than 10% with respect to the result of the infinite-order theory. We expect that the procedure will also give acceptable results for non-resonant interactions, where the Margenau treatment does not apply.     

Theory of the line shape of gamma-photon transitions

There is a discussion of the line shape for the nuclear two-quantum transition due to the simultaneous absorption of a Mossbauer quantum and a quantum from a classical photon source. The problem is solved through the use of density-matrix equations, and an equation is derived for the intensity of absorbed gamma rays. In contrast with the case of the ordinary probabilistic approach, the equation for the intensity of gamma absorption reveals a dependence on the relaxation times within the ground and excited states. The line shape for gamma-photon transitions for low intensities of the incident radiation usually differs little from the shape of the Mossbauer line. However, at large irradiation intensities, a shift and a broadening of the resonant lines occur, proportional to the radiation power. These corrections must be taken into account in, e.g., gamma-magnetic resonance.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 12, No. 7, pp. 24–30, July, 1969.     

On the theories of cyclotron resonance line shape

A recent claim by Choi and Chung that the Argyres-Sigel theory of cyclotron resonance line shape is invalid is shown to be erroneous.     

Theory of ferromagnetic resonance line shape in insulators

The paper discusses the absorption of the energy of a high-frequency field by a magnetic sample from the point of view of the interaction of spin waves with photons and spin waves amongst themselves. A general expression for the form of the absorption curve is derived, using the method known from the quantum theory of radiation and assuming very weak fields.

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The author thanks S. Krupika, Candidate of Sciences, for the exceptional interest taken in this work, for advice and a number of helpful and critical remarks.     

晶体X射线衍射线形状的理论推导

考虑到不同深度的晶面对X射线吸收的差别,导出了X射线衍射线形状的曲线,获得了精确的衍射曲线形状的表达式,讨论了吸收对衍射峰形状的影响．最后还对理论与实验结果进行了比较．     

The experimental investigation of the spin packet line shape in an inhomogeneous magnetic resonance line

It is shown that the saturation transient of an inhomogeneous spin system is strongly affected not only by the width but also by the shape of the spin packets. In two cases of main interest, Lorentzian and Gaussian packets, we report approximate analytical expressions of χ(t) during the saturation transient, with which the experimental results may be compared. By this method we give experimental evidence that the packet profile in dilute ruby samples has a Gaussian shape.     

Intracavity absorption line shape and the super-regen model

Intracavity absorption has been observed in a short lived excited state of helium produced in an RF discharge inside the dye laser cavity. The line shape consists of an absorption feature with two symmetric enhancement wings. The central absorption feature is considerably broadened over the natural width, and this is shown to be in agreement with the superregen model. It is also shown that under certain conditions the ICA signal inverts so that the central feature becomes enhanced and the symmetric wings appear as absorption. This result is also in agreement with predictions of the model.     

Disorder effects on the Raman line shape in ZrO2

Experimental data obtained by Lughi and Clarke [5] are compared to the theory describing disorder effects on optical phonons. Sharpening and vanishing of the asymmetry of the Raman lines after annealing are attributed to a decrease in short-range disorder. The parameters of disorder (such as the phonon-defect coupling and the correlation length) are defined in the comparison. The text was submitted by author in English.