Showing papers on "Resonance published in 1996"

Vibrations of free and surface‐coupled atomic force microscope cantilevers: Theory and experiment

Abstract: With an optical interferometer, the free vibration spectra and the local vibration amplitude of four rectangular atomic force microscope cantilevers made of silicon have been examined experimentally in a spectral range of 100 kHz to 10 MHz. A good agreement with the flexural wave theory of elastic beams was found. Coupling to torsional vibrations was also observed. When the sensor tip of the cantilever is in contact with a sample surface the resonances are shifted in frequency and the vibration amplitudes along the cantilever change. A method is presented to calculate this frequency shift using a linear approximation for the tip–sample interaction forces, and the results are compared with the frequency shift calculated from the point‐mass model. The measured resonance frequencies of a surface‐coupled cantilever do not correspond as well to the theoretical ones as in the free case even if the elastic‐beam model is used. The reason for the disagreement is found to be the geometry of the commercial cantileve...

Influence of Nearly Resonant Light on the Scattering Length in Low-Temperature Atomic Gases.

Abstract: We develop the idea of manipulating optically the scattering length $a$ in low-temperature atomic gases. If the incident light is close to resonance with one of the bound $p$ levels of electronically excited molecules, virtual radiative transitions of a pair of interacting atoms to this level can significantly change the value and even reverse the sign of $a$. The decay of the gas due to photon recoil and due to photoassociation can be minimized by selecting the frequency detuning and the Rabi frequency. Our calculations show the feasibility of optical manipulations of trapped Bose condensates through a light-induced change in the mean field interaction between atoms, which is illustrated for ${}^{7}\mathrm{Li}$.

Biophysical techniques in photosynthesis

Abstract: Preface. Part One: Optical Methods. 1. Developments in Classical Optical Spectroscopy J. Amesz. 2. Linear and Circular Dichroism G. Garab. 3. Fluorescence K. Sauer, M. Debreczeny. 4. Ultrafast Spectroscopy of Photosynthetic Systems R. Jimenez, G.R. Fleming. 5. Data Analysis of Time-Resolved Measurements A.R. Holzwarth. 6. Photosynthetic Thermoluminescence as a Simple Probe of Photosystem II Electron Transport Y. Inoue. 7. Accumulated Photon Echo Measurements of Excited State Dynamics in Pigment-Protein Complexes T.J. Aartsma, R.J.W. Louwe, P. Schellenberg. 8. Spectral Hole Burning: Methods and Applications to Photosynthesis N. Raja, S. Reddy, G.J. Small. 9. Infrared and Fourier-Transform Infrared Spectroscopy W. Mantele. 10. Resonance Raman Studies in Photosynthesis - Chlorophyll and Carotenoid Molecules B. Robert. 11. Stark Spectroscopy of Photosynthetic Systems S.G. Boxer. 12. The Photoacoustic Method in Photosynthesis - Monitoring and Analysis of Phenomena which Lead to Pressure Changes Following Light Excitation S. Malkin. Part Two: Magnetic Resonance. 13. Magnetic Resonance: an Introduction A.J. Hoff. 14. Time-Resolved Electron Paramagnetic Resonance Spectroscopy - Principles and Applications H. Levanon. 15. Electron Spin Echo Methods in Photosynthesis Research R.D. Britt. 16. ENDOR Spectroscopy W. Lubitz, F. Lendzian. 17. Optically Detected Magnetic Resonance (ODMR) of Triplet States in Photosynthesis A.J. Hoff. 18. MagicAngle Spinning Nuclear Magnetic Resonance of Photosynthetic Components H.J.M. de Groot. Part Three: Structure and Oxygen. 19. Structure Determination of Proteins by X-Ray Diffraction M. Schiffer. 20. Electron Microscopy E.J. Boekema, M. Roegner. 21. X-Ray Absorption Spectroscopy:Determination of Transition Metal Site Structures in Photosynthesis V.K. Yachandra, M.P. Klein. 22. Moessbauer Spectroscopy P.G. Debrunner. 23. Characterization of Photosynthetic Supramolecular Assemblies Using Small Angle Neutron Scattering D.M. Tiede, P. Thiyagarajan. 24. Measurements of Photosynthetic Oxygen Evolution H.J. van Gorkom, P. Gast.

QCM Operation in Liquids: An Explanation of Measured Variations in Frequency and Q Factor with Liquid Conductivity

Abstract: Recently, several reports have shown that when one side of a quartz crystal microbalance (QCM) is exposed to a liquid, the parallel (but not the series) resonant frequency is influenced by the conductivity and dielectric constant of the liquid. The effect is still controversial and constitutes a serious complication in many applications of the QCM in liquid environments. One suggestion has been that acoustically induced surface charges couple to charged species in the conducting liquid. To explore this effect, we have measured the parallel and the series mode resonance frequencies, and the corresponding Q factors, for a QCM with one side facing a liquid. These four quantities have all been measured versus liquid conductivity, using a recently developed experimental setup. It allows the simultaneous measurement of the resonant frequency and the Q factor of an oscillating quartz crystal, intermittently disconnected from the driving circuit. Based on these results, a simple model together with an equivalent circuit for a quartz crystal exposed to a liquid is presented. The analysis shows that it is not necessary to infer the existence of surface charges (or other microscopic phenomena such as electrical double layers) to account for the influence of the liquid's electrical properties on the resonant frequency. Our results show that the contacting conductive liquid, in effect, enlarges the electrode area on the liquid side and thereby changes the parallel resonant frequency. By proper design of the QCM measurement, perturbing effects due to the liquid's electrical properties can be circumvented.

High sensitivity surface plasmon resonace sensor based on phase detection

Abstract: A surface plasmon resonance sensing technique based on optical heterodyne phase detection is presented. The theoretical sensitivity of this new method is compared with traditioal surface plasmon resonance technique. The results of phase detection modeling shows a strong dependence on sensor film thickness. With a practical configuration, the resolution of refractive index is predicted to be 5 × 10 −7 refractive index units. An experimental set-up is described and the initial results presented conincide with the theoretical prediction.

Atomic Data for Permitted Resonance Lines of Atoms and Ions from H to Si, and S, Ar, Ca and Fe

Abstract: We list vacuum wavelengths, energy levels, statistical weights, transition probabilities and oscillator strengths for permitted resonance spectral lines of all ions of 18 astrophysically important elements (H through Si, S, Ar, Ca, Fe). Using a compilation of experimental energy levels, we derived accurate wavelengths for 5599 lines of 1828 ground-term multiplets which have gf-values calculated in the Opacity Project. We recalculated the Opacity Project multiplet gf-values to oscillator strengths and transition probabilities of individual lines. For completeness, we added 372 resonance lines of NeI, ArI, FeI and FeII ions which are not covered by the Opacity Project. Intercombination and forbidden lines are not included in the present compilation.

Size‐selected vibrational spectra of phenol‐(H2O)n (n=1–4) clusters observed by IR–UV double resonance and stimulated Raman‐UV double resonance spectroscopies

Abstract: OH and CH stretching vibrations of bare phenol, phenol‐(H2O)n clusters (n=1–4), and partially deuterated clusters in the S0 state were observed by using IR–UV double resonance and stimulated Raman‐UV double resonance spectroscopies. Characteristic spectral features of the OH stretching vibrations of the phenol as well as of the H2O sites were observed, which are directly related to their structures. The cluster structures were investigated by comparing the observed spectra with the calculated ones obtained by the ab initio molecular orbital calculation with (self‐consistent field) SCF 6‐31G and SCF 6‐31G* basis sets given by Watanabe and Iwata. It was found that for the clusters with n≥2, the isomer of ring form hydrogen‐bonded structure is most stable and the simulated IR spectra based on the calculated structure showed good agreements with the observed ones. For a particular cluster, which was assigned as an isomer of the n=4 cluster, an anomalous IR spectrum was observed. Two forms of the isomer are proposed with respect to the structure of water moiety: (1) an ‘‘ice’’ structure and (2) an ‘‘ion‐pair’’ structure. The relative IR absorption cross sections of each bands were also investigated for the clusters with n=1 to 4. It was found that the IR absorption cross section of the phenolic OH stretching vibration of the n=1 cluster increases by a factor of 6 compared to that of bare phenol and it further increases with the cluster size.

Generation and detection of photons in a cavity with a resonantly oscillating boundary

Abstract: The problem of photon creation from vacuum in an ideal cavity with vibrating walls is studied in the resonance case, when the frequency of vibrations equals twice the frequency of some unperturbed electromagnetic mode. Analytical solutions are obtained in two cases: for the one-dimensional model (scalar electrodynamics) and for the three-dimensional (3D) cavity. In the first example, we have a strong intermode interaction; nonetheless, an explicit solution in terms of the complete elliptic integrals is found. The rate of photon generation in the principal mode rapidly assumes a constant value proportional to the product of the frequency by the dimensionless amplitude of oscillations. The total amount of photons created in all the modes increases in time as ${\mathit{t}}^{2}$. In the second example, the eigenmode spectrum is nonequidistant and the problem can be reduced to the problem of a single harmonic oscillator with a time-dependent frequency. The number of photons in the resonant mode of a 3D cavity increases exponentially in time and the field appears in a highly squeezed state with a strongly oscillating photon distribution function. The problem of detecting the created photons is analyzed in the framework of a simplified model, when a detector is replaced with a harmonic oscillator. It turns out that the presence of the detector changes the picture drastically: both the detector and the field mode occur in highly mixed (nonthermal) quantum states, with identical nonoscillating photon distribution functions. The detector gains exactly half of the total energy of excitation inside the cavity. The estimations show a possibility of creating up to several hundred or even thousand photons, provided that the cavity's Q factor exceeds ${10}^{10}$ and the amplitude of the wall's oscillations is greater than ${10}^{\mathrm{\ensuremath{-}}10}$ cm at a frequency of the order of 10 GHz. \textcopyright{} 1996 The American Physical Society.

Resonance and elastic nonlinear phenomena in rock

Abstract: In a great variety of laboratory experiments over large intervals in stress, strain, and frequency, rocks display pronounced nonlinear elastic behavior. Here we describe nonlinear response in rock from resonance experiments. Two important features of nonlinear resonant behavior are a shift in resonant frequency away from the linear resonant frequency as the amplitude of the disturbance is increased and the harmonics in the time signal that accompany this shift. We have conducted Young's mode resonance experiments using bars of a variety of rock types (limestone, sandstone, marble, chalk) and of varying diameters and lengths. Typically, samples with resonant frequencies of approximately 0.5-1.5 kHz display resonant frequency shifts of 10% or more, over strain intervals of 10 -7 to 10 -6 and under a variety of saturation conditions and ambient pressure conditions. Correspondingly rich harmonic spectra measured from the time signal progressively develop with increasing drive level. In our experiments to date, the resonant peak is observed to always shift downward (if indeed the peak shifts), indicating a net softening of the modulus with drive level. This observation is in agreement with our pulse mode and static test observations, and those of other researchers. Resonant peak shift is not always observed, even at large drive levels ; however, harmonics are always observed even in the absence of peak shift when detected strain levels exceed 10 -7 or so. This is an unexpected result. Important implications for the classical perturbation model approach to resonance results from this work. Observations imply that stress-strain hysteresis and discrete memory may play an important role in dynamic measurements and should be included in modeling. This work also illustrates that measurement of linear modulus and Q must be undertaken with great caution when using resonance.

Reduction of Cytochrome c by Halide-Modified, Laser-Ablated Silver Colloids

Abstract: Silver colloids of 20 nm mean particle diameter were prepared by laser ablation and modified by adsorption of iodide and bromide ions. Addition of cytochrome c to this colloid resulted in the reduction of the protein, which was monitored by surface-enhanced resonance Raman scattering and absorption spectroscopies. Colloidal metal films, prepared from the same Ag colloid, were employed to minimize contributions from aggregation. Effects of surface modification on the Ag plasmon resonance were studied in both colloidal suspensions and colloidal metal films. The conclusion was made that adsorption of I- and Br- results in charging of the Ag particle as a whole and a shift of its potential to more negative values. The donated charge is delocalized in a thin surface layer and does not significantly affect the plasmon resonance frequency of the particle.

Off-Resonance Conduction Through Atomic Wires

Abstract: The electrical resistance of wires consisting of either a single xenon atom or two xenon atoms in series was measured and calculated on the basis of an atom-jellium model. Both the measurement and the calculation yielded a resistance of 10(5) ohms for the single-xenon atom system and 10(7) ohms for the two-xenon atom system. These resistances greatly exceeded the 12,900-ohm resistance of an ideal one-dimensional conduction channel because conduction through the xenon atoms occurs through the tail of the xenon 6s resonance, which lies far above the Fermi level. This conduction process in an atom-sized system can now be understood in terms of the electronic states of individual atoms.

Models of subthreshold membrane resonance in neocortical neurons

Abstract: 1 We obtained whole cell data from sensorimotor cortical neurons of in vitro slices (juvenile rats) and observed a low-frequency resonance (1-2 Hz) in their voltage responses We constructed models of subthreshold membrane currents to determine whether a hyperpolarization-activated cation current (IH) is sufficient to account for this resonance 2 Parameter values for a basic IH (BH) model were estimated from voltage-clamp experiments at room temperature The BH model formed a component of a reduced membrane (RM) model On numerical integration, the RM model exhibited voltage sags and rebounds to injected current pulses; maximal voltage responses to injected oscillatory currents occurred near 2 Hz 3 We compared the experimentally measured frequency-response curves (FRCs) at room temperature with the theoretical FRCs derived from the RM model The theoretical FRCs exhibited resonant humps with peaks between 1 and 2 Hz At 36 degrees C, the theoretical FRCs peaked near 10 Hz The characteristics of theoretical and observed FRCs were in close agreement, demonstrating that IH is sufficient to cause resonance Thus we classified IH as a resonator current 4 We developed a technique, the reactive current clamp (RCC), to inject a computer-calculated current corresponding to a membrane ionic current in response to the membrane potential of the neuron This enabled us to study the interaction of an artificial ionic current with living neurons (electronic pharmacology or EP-method) Using the RCC, a simplified version of the BH model was used to cancel an endogenous IH (electronic antagonism) and to introduce an artificial IH (electronic expression) when an endogenous IH was absent Antagonism of IH eliminated sags and rebounds, whereas expression of IH endowed neurons with resonance and the frequency-selective firing that accompanies resonance in neurons with an endogenous IH Previous investigations have relied on the specificity of pharmacological agents to block ionic channels, eg, Cs+ to block IH However, Cs+ additionally affects other currents This represents the first time an in vitro modeling technique (RCC) has been used to antagonize a specific endogenous current, IH 5 A simplified RM model yielded values of the resonant frequency and Q (an index of the sharpness of resonance), which rose almost linearly between -55 and -80 mV Resonant frequencies could be much higher than fH = (2 pi tau H) - 1 where tau H is the activation time constant for IH 6 In the FRCs, resonance appeared as a hump at intermediate frequencies because of low- and high-frequency attenuations due to IH and membrane capacitance, respectively Changing the parameters of IH altered the low-frequency attenuation and, hence, the resonance Changes in the leak conductance affected both the low- and high-frequency attenuations 7 We modeled an inwardly rectifying K+ current (IIR) and a persistent Na+ current (INaP) to study their effects on resonance Neither current produced resonance in the absence of IH We found that IIR attenuated, whereas INaP amplified resonance Thus IIR and INaP are classified as attenuator and amplifier currents, respectively 8 Resonators and attenuators differ in that they have longer and shorter time constants, respectively, compared with the membrane time constant Therefore, an increase in the leak conductance decreases the membrane time constant, which can transform an attenuator into a resonator, altering the frequency response This suggests a novel mechanism for modulating the frequency responses of neurons to inputs 9 These investigations have provided a theoretical framework for detailed understanding of mechanisms that produce resonance in cortical neurons Resonance is one aspect of the intrinsic rhythmicity of neurons The rhythmicity due to IH resonance is latent until it is revealed by oscillatory inputs (ABSTRACT TRUNCATED)

Inverse Bloch oscillator: Strong terahertz-photocurrent resonances at the Bloch frequency.

Abstract: We have observed the inverse Bloch oscillator effect: resonant changes in the current-voltage characteristics of miniband semiconductor superlattices when the Bloch frequency is resonant with a terahertz field and its harmonics. The resonances consist of a peak in the current accompanied by a decrease of the current at the low bias side. At the highest intensities we observe up to a four-photon resonance. This is an analog of Shapiro steps in a S-I-S junction caused by the ac Josephson effect. The increase of the current is caused by stimulated emission of photons and we can estimate the THz gain of the superlattice from the induced current at the resonance.

Observation of ferromagnetic resonance in a microscopic sample using magnetic resonance force microscopy

Abstract: We report the observation of a ferromagnetic resonance signal arising from a microscopic (∼20 μm×40 μm) particle of thin (3μm) yttrium iron garnet film using magnetic resonance force microscopy (MRFM). The large signal intensity in the resonance spectra suggests that MRFM could become a powerful microscopic ferromagnetic resonance technique with a micron or sub‐micron resolution. We also observe a very strong nonresonance signal which occurs in the field regime where the sample magnetization readily reorients in response to the modulation of the magnetic field. This signal will be the main noise source in applications where a magnet is mounted on the cantilever.

Comparison of TOF-ERDA and nuclear resonance reaction techniques for range profile measurements of keV energy implants

Abstract: A comparative study on the range measurements of keV energy implants by the Time-of-Flight Elastic Recoil Detection Analysis (TOF-ERDA) and conventionally used nuclear resonance reaction methods has been performed for 20–100 keV 15N+ ions implanted into crystalline silicon. Range profiles of 15N atoms were chosen because they can be measured accurately using a very strong and narrow resonance at Ep = 429.6 keV in the reaction 15N(p,αγ)12C which provides a challenging test for other methods. The measured range profiles were simulated by molecular dynamics calculations where the interatomic NSi pair potential is deduced from first principles calculations. The electronic stopping power for 20–100 keV nitrogen ions in silicon is deduced from the comparison of the measured and simulated range profiles. The results are discussed in the framework of the applicability of the TOF-ERDA technique for keV energy ion range measurements.

Method for performing on-wafer tuning of thin film bulk acoustic wave resonators (FBARS)

Abstract: A method for tuning a Thin Film Bulk Acoustic Wave Resonator (FBAR) located on a wafer. The FBAR comprises a plurality of layers having respective thicknesses. The FBAR exhibits at least one of a series resonance and a parallel resonance at respective frequencies that are a function of the thickness of at least one of the layers. A first step of the method includes measuring a frequency at which the FBAR exhibits one of a series resonance and a parallel resonance. A next step includes calculating an amount (A) by which the thickness of the at least one layer needs to be altered in order to minimize a difference between the measured frequency and a reference frequency. A further step includes altering the thickness of the at least one layer by the amount (A).

The unimolecular dissociation of HCO. II. Comparison of calculated resonance energies and widths with high‐resolution spectroscopic data

Abstract: We present a theoretical study of the unimolecular dissociation resonances of HCO in the electronic ground state, X1A′, using a new ab initio potential energy surface and a modification of the log‐derivative version of the Kohn variational principle for the dynamics calculations. Altogether we have analyzed about 120 resonances up to an energy of ≊2 eV above the H+CO threshold, corresponding to the eleventh overtone in the CO stretching mode (v2=11). The agreement of the resonance energies and widths with recent stimulated emission pumping measurements of Tobiason et al. [J. Chem. Phys. 103, 1448 (1995)] is pleasing. The root‐mean‐square deviation from the experimental energies is only 17 cm−1 over a range of about 20 000 cm−1 and all trends of the resonance widths observed in the experiment are satisfactorily reproduced by the calculations. The assignment of the states is discussed in terms of the resonance wave functions. In addition, we compare the quantum mechanical state‐resolved dissociation rates ...

Conformational Properties of Nickel(II) Octaethylporphyrin in Solution. 1. Resonance Excitation Profiles and Temperature Dependence of Structure-Sensitive Raman Lines

Abstract: We have measured polarized resonance Raman spectra of nickel(II) octaethylporphyrin in CS2 and CH2Cl2 solution at different excitation wavelengths (430−580 nm) and temperatures (190−310 K). The analysis of the spectra revealed that the structure-sensitive Raman lines ν19 and ν10 can be decomposed consistently into two sublines for all excitation wavelengths and temperatures. In the resonance region of the QO and QV bands, the 0−1 and 0−0 resonances in the excitation profiles of the low-frequency (LF) sublines of ν19 and ν10 are red-shifted by (150 (30) cm-1 with respect to the sublines that are at higher frequencies (HF). In accordance with experimental and theoretical results, this indicates that the LF sublines of ν19 and ν10 result from a nonplanar conformer, whereas the HF sublines correspond to an almost planar conformer. The existence of this known conformational equilibrium in solution is further corroborated by the van't Hoff behavior of the intensity ratios ILF/IHF of the sublines of ν19 and ν10....

Theory of resonance Raman optical activity: the single electronic state limit

Abstract: The theory of natural Raman optical activity (ROA) is extended to the limit of strong resonance with a single electronic state (SES). It is shown that in the SES limit, the resonance ROA (RROA) bands all have the same sign, and their relative intensities are identical to the corresponding resonance Raman (RR) parent bands. The sign of the RROA bands are predicted to be opposite that of the pure electronic circular dichroism (CD) of the single, resonant electronic transition. The ratio of the RROA to the RR spectrum is the same or one-half the magnitude of the electronic CD anisotropy ratio of the resonant electronic state. Deviation from this simple pattern is indicative of contributions from more than one excited electronic state to the RR and RROA spectra, and hence is a sensitive probe of the electronic origin of ordinary RR spectra.

Solvent Effects in the Raman Spectra of the Triiodide Ion: Observation of Dynamic Symmetry Breaking and Solvent Degrees of Freedom

Abstract: Resonance Raman spectra, including absolute cross sections, have been measured for the triiodide ion in ethanol, ethyl acetate, and acetonitrile solvents using eight excitation wavelengths that span the two lowest absorption bands. Preresonance Raman spectra have also been obtained with 488 nm excitation. The apparent vibrational line widths observed on resonance are approximately twice the preresonant line widths in all three solvents. By quantitatively modeling the triiodide/solvent system using two intramolecular modes (the symmetric and antisymmetric stretches) and one low-frequency intermolecular or solvent mode, we are able to reproduce the vibrational broadening on resonance, which, within the context of our model, is due to unresolved combination bands between the intramolecular degrees of freedom and the intermolecular mode. The Raman spectra in ethanol clearly show one-quantum transitions in the antisymmetric stretching mode (ν3) which should be symmetry forbidden in the linear D∞h geometry, ind...

Vacuum compatible high-sensitive Kelvin probe force microscopy

Abstract: A vacuum compatible Kelvin probe force microscopy (KPFM) is presented. Difficulties in operating KPFM in a vacuum were overcome by utilizing the direct cantilever resonance frequency detection in the tip height control whereas the indirect resonance frequency detection scheme was used in primordial KPFM. The potential measurement sensitivity was improved by 14 dB compared to that in air. It is due to the increased cantilever Q value and the reduction in the interference from the tip height detection signal because potential measurement is conducted using the cantilever’s second resonance while tip height control was conducted using the first resonance. A silicon wafer whose surface is partially doped with arsenic by ion implantation was observed, and surface potential difference at the junctions were clearly imaged.

Elastic constants and their temperature dependence for the intermetallic compound Ti3Al

Abstract: Single-crystal elastic contents of Ti3Al have been measured from 3.3 to 290K by a rectangular parallelepiped resonance method. The elastic anisotropy of Ti3Al is similar to, but slightly larger than, that of pure Ti. The values of the measured elastic constants are compared with those calculated for pure Ti stressed to such an extent that it has the same lattice constants as Ti3Al. The difference is interpreted as indicating the existence of directional bonding in the compound.

Light modulation with resonant grating–waveguide structures

Abstract: Resonant grating–waveguide structures formed with InP/InGaAsP semiconductor materials were tested to show light modulation at a wavelength of 1.55 μm. Narrow, subnanometer resonant spectral bandwidths and a ratio of reflected intensities between resonance and away from resonance of greater than 50 were measured. For a resonant structure with an area of 3 mm × 3 mm, the modulation frequency reached 5 MHz.

Natural convection in an enclosure having a vertical sidewall with time-varying temperature

Abstract: A numerical study is performed for time-varying natural convection of an incompressible Boussinesq fluid in a sidewall-heated square cavity. The temperature at the cold sidewall Tc is constant, but at the hot sidewall a time-varying temperature condition is prescribed, . Comprehensive numerical solutions are found for the time-dependent Navier–Stokes equations. The numerical results are analysed in detail to show the existence of resonance, which is characterized by maximal amplification of the fluctuations of heat transfer in the interior. Plots of the dependence of the amplification of heat transfer fluctuations on the non-dimensional forcing frequency ω are presented. The failure of Kazmierczak & Chinoda (1992) to identify resonance is shown to be attributable to the limitations of the parameter values they used. The present results illustrate that resonance becomes more distinctive for large Ra and Pr ∼ 0(1). The physical mechanism of resonance is delineated by examining the evolution of oscillating components of flow and temperature fields. Specific comparisons are conducted for the resonance frequency ωr between the present results and several other previous predictions based on the scaling arguments.

Parameters of lossy cavity resonators calculated by the finite element method

Abstract: The calculation of the resonance frequency and quality factor of closed or aperture coupled cavity resonators with volume and wall losses by an edge finite element method is discussed. An efficient solver is developed to solve the complex nonlinear eigenvalue problem. The effect of the roughness of the walls on the quality factor is taken approximately into account.