Inhomogeneous and homogeneous broadening effects onnuclear resonance experiments

Inhomogeneous broadening of resonance lines causes a reduction of absorption in nuclear resonance experiments. This is particularly devastating to the observation of the Mössbauer effect in isomers like ¹⁰⁷Ag with a half-life of 44s.It has been suggested in the literature that homogeneous broadening can provide overlap of resonance lines and thus theMössbauer effect can be recovered. The analysis presented in this paper shows that this is not the case for Mössbauer experiments, unless the radiative width Γ_Γ also increases. Although overlap occurs when the lines are homogeneously broadened to a total width Γ_{_}H which exceeds the natural width Γ, and the inhomogeneous width Δ, the Mössbauer absorption remains low because it is proportional to the factor of Γ_γ/Γ _H.     

Mode selection by homogeneous broadening and non-linear absorption

A continuously tunable single mode can be selected from a multimode spectrum of a laser by non-linear absorbers. Theoretical and experimental investigations show that the selectivity of the method and the power of the selected mode depend considerably on the ratio of the saturation parameters of the amplifying and absorbing medium. With a He∶Ne laser having an active length of 1.70 m, a power of 35 mW was obtained in single-mode operation.     

Stability criteria for lasers with mixed line broadening

The stability criteria governing the behaviour of laser oscillators are becoming increasingly well understood, and it is found that for practical applications two types of criteria must usually be distinguished. For lasers in the inhomogeneous limit these two types are essentially equal, and this study explores their behaviour as the degree of inhomogeneous broadening is varied. All lasers exhibit a combination of homogeneous and inhomogeneous line broadening, and the graphical results presented here may be used for predicting or interpreting single-mode instabilities in practical oscillators with arbitrary mixed line broadening.     

Metastable states in homogeneous Ising models

Metastable states of homogeneous 2D and 3D Ising models are studied under free boundary conditions. The states are defined in terms of weak and strict local minima of the total interaction energy. The morphology of these minima is characterized locally and globally on square and cubic grids. Furthermore, in the 2D case, transition from any spin configuration that is not a strict minimum to a strict minimum is possible via non-energy-increasing single flips.     

Micromaser line broadening without photon exchange

We perform a calculation of the linewidth of a micromaser, using the master equation and the quantum regression approach. A `dephasing' contribution is identified from pumping processes that conserve the photon number and do not appear in the photon statistics. We work out examples for a single-atom maser with a precisely controlled coupling and for a laser where the interaction time is broadly distributed. In the latter case, we also assess the convergence of a recently developed uniform Lindblad approximation to the master equation; it is relatively slow.     

Anomalous homogeneous optical absorption line broadening of Eu3+ in superionic PbF2

Homogeneous broadening of one of the ⁵D₁←⁷F₀ absorption lines of Eu³⁺ in PbF₂ was measured in the temperature range 300–800 K. Below 625 K the linewidth depends linearly on T; above 625 K it increases rapidly followed by a plateau beginning near 700 K. This behavior is quite distinct from that expected for the normal Raman process in crystalline materials and appears to be correlated with F^- ion motion responsible for the superionic conductivity of PbF₂.     

A new calculation for line broadening of Lyman-α in plasmas

A line-shape calculation of Ly-α is presented which uses a new method based on operator-valued temporal correlation functions.     

Resonance fluorescence and Raman line shapes produced by monochromatic laser fields: Effects of branching ratio and homogeneous broadening

The Heitler-Ma damping theory is developed for a two level system in which the excited state is homogeneously, and irreversibly coupled to various continuum states with a total decay rate 1/τ. We give particular consideration to the channel consisting of a third, discrete, atomic level and a continuum of emitted photons, which simply corresponds to a spontaneous resonant Raman process. The theory applies to either a narrow, pulsed, laser beam, or injection of target atoms or molecules into a c.w. field.In this paper, we examine the t=∞ spectra as a function of field strength, detuning from resonance, and especially as a function of the upper state broadening, characterized by the branching ratio f_A=τ/t_A, where τ^-_A is the natural resonance fluorescence lifetime. For strong fields, we obtain the usual resonance fluorescence spectrum centered at the incident, pumping frequency, with two symmetric side bands displaced by the Rabi frequency. If f_A→0, the spectrum approaches the one-photon limit, with the height of the side bands equal to $\text{1}\text{2}$ that of the central peak and all of equal width. In this limit, the target predominantly decays into the Raman or other irreversible channels, and only a single laser photon contributes to the extremely weak resonance spectrum. At the opposite extreme, f_A→1, the target scatters many photons out of the laser-field before it is optically pumped into a non-interacting state and the spectrum exhibits the infinite cascade properties obtained by Mollow. The side bands become broadened, with a height equal to $\text{1}\text{3}$ of the central peak. In this theory, we obtain a more complete interpretation of the elastically scattered delta function, which is an artifact of the infinite lifetime of the atom in the usual two-level theories. In both limits of f_A, we obtain a Raman lineshape which is unchanged and is simply a function of the total width ?/τ of the excited state.     

Strong-field double optical resonance with two kinds of homogeneous broadening

We study the absorption spectrum of a probe field in a two-level atomic system excited by a strong laser field in the presence of both collisional and laser dephasing processes. We show that the effects of these two kinds of homogeneous broadening on the absorption line shape are quite different.     

Magnetic field dependence of cyclotron-resonance line broadening

We report that for non-degenerate electrons an electron-impurity interaction with a screening radius larger than the cyclotron orbit radius yields a cyclotron-resonance line broadening, which decreases with increasing magnetic field. This is consistent with most measured results.     

On the broadening of the annihilation line

The broadening of annihilation line was studied with a Ge detector. The annihilation line was deconvoluted taking into account the instrumental resolution of 1.08 keV. The P_f in several metals are found. The contribution of core electrons to annihilation is deduced.     

Correlations in the quantum theory of plasma line broadening

A unified theory of plasma line broadening is obtained from a quantum kinetic equation, paralleling existing results for a classical plasma. The atom-electron interactions are shielded by equilibrium electron correlation functions and a frequency dependent dielectric function. A “ring” approximation is used to replace the classical plasma parameter expansion, for typical laboratory conditions. Atom-electron correlations are included as well as electron-electron correlations.     

Estimate of inhomogeneous line broadening in steady-state magnetic resonance

We have established relationships between the experimental and theoretical absorption and dispersion line parameters for steady-state magnetic resonance, allowing us to determine both the field characteristics (amplitude of the a.c. magnetic field) and the relaxation characteristics (longitudinal and transverse relaxation times) of the object under study.     

Coherent resonance line broadening effects in absorptive optical bistability

The effect of resonant exchange of quanta between coherently driven atoms on absorptive bistability is examined. Expressions for the variation of the effect with density are presented.