Masatoshi Misono

Stochastic resonance in an optical bistable system driven by colored noise

Stochastic resonance (SR) in an optical bistable system is studied experimentally. The resonance signal peculiar to SR was observed, and the dependence of the resonance signal on the noise correlation time was studied. The experiment is numerically simulated by using a bistable potential and exponentially correlated Gaussian noise. The numerical simulation reproduces well the experimental results.

The Doppler-free two-photon absorption spectroscopy of naphthalene with Zeeman effects

The Doppler-free spectrum and the Zeeman effect of the A 1B1u(v4=1:b1u)←X 1Ag(v=0) transition of naphthalene in the 33 576.4–33 578.0 cm−1 range has been measured by means of two-photon absorption spectroscopy with counter propagating light beams of identical wavelength within an external cavity. Rotational lines were fully resolved, and 1098 Q(K)Q(J) lines of J=0–42, K=0–24 were assigned. The molecular constants of the A 1B1u(v4=1:b1u) state were determined. Deviations from the line positions calculated using the molecular constants were observed for several lines. Perturbations were not observed for K=0 but were observed to increase with increasing K. The perturbations were therefore identified as originating from a parallel Coriolis interaction. The Zeeman splittings for lines of a given J were observed to be maximum at K=0 and to decrease with increasing K. Analysis of these results indicate that the magnetic moment lies along the c axis (perpendicular to the molecular plane). Any lines broader than o...

Doppler-free two-photon absorption spectroscopy and the Zeeman effect of the A 1B2u←X 1A1g1401101 band of benzene

A Doppler-free absorption spectrum and the Zeeman effect of the A 1B2u(v14=1,v1=1)←X 1A1g(v=0) transition of benzene have been measured by means of two-photon absorption spectroscopy with counterpropagating light beams of identical wavelength within an external cavity. Rotational lines were fully resolved, and 647 QQ lines of J=0–43, K=0–43 have been assigned. The molecular constants of the A 1B2u(v14=1,v1=1) state have been determined as A=B=0.181 046 1, C=0.090 548 9, DJ=0.544×10−7, DJK=−1.093×10−7, DK=0.587×10−7, and T0=40 578.2672 cm−1. The Zeeman splittings for lines of a given J were observed to increase regularly with K and reach a maximum at K=J. This demonstrates that the magnetic moment lies along the c axis (perpendicular to the molecular plane). The magnetic moment of the A 1B2u(v14=1,v1=1,J=43,K=43) level was determined to be 0.005μB. The Zeeman splittings of the K=J levels were observed to increase with increasing J. Via analysis of the rotationally resolved Zeeman spectra, it is concluded t...

Doppler-free two-photon excitation spectroscopy and the Zeeman effects of the S1B1u1(v21=1)←S0Ag1(v=0) band of naphthalene-d8

Doppler-free two-photon excitation spectrum and the Zeeman effect of the S1 1B1u(v21=1) <-- S0 1Ag(v=0) transition of naphthalene-d8 have been measured. 908 lines of Q(Ka)Q(J)KaKc transition of J=0-41, Ka=0-20 were assigned, and the molecular constants of the S1 1B1u(v21=1) state were determined. Perturbations were observed, and those were identified as originating from Coriolis interaction. No perturbation originating from an interaction with triplet state was observed. The Zeeman splittings from lines of a given J were observed to increase with Kc, and those of the Kc=J levels increased linearly with J. The Zeeman effects are shown to be originating from the magnetic moment of the S1 1B1u state, which is along the c axis and is induced by mixing of the S2 1B3u state to the S1 1B1u state by J-L coupling. Rotationally resolved levels were found not to be mixed with a triplet state from the Zeeman spectra. Accordingly, it is concluded that nonradiative decay of an isolated naphthalene excited to low rovibronic levels in the S1 1B1u state does not occur through the intersystem mixing. This is at variance with generally accepted understanding of the pathways of the nonradiative decay.

Coherence Resonance in a Schmitt-Trigger Inverter with Delayed Feedback

We study the coherence resonance in a Schmitt-trigger inverter with a delayed feedback loop. The output of the system is analyzed changing the input noise amplitude and the delay time of the feedback loop. The regularity of the output shows resonance-like dependence on the input noise amplitude. At the optimum input noise amplitude, the system outputs well-regulated rectangular wave, and corresponding peaks in the output spectrum become large and sharp. This optimization of the system is accomplished when the period of the output rectangular wave almost coincides with the feedback delay time.

Zeeman spectra of the à 1Au←X̃ 1Ag transition of trans-glyoxal studied by Doppler-free two-photon fluorescence excitation spectroscopy

Doppler-free two-photon fluorescence excitation spectra of the A 1Au(v7′=1)←X 1Ag(v″=0) transition of trans-glyoxal were measured by propagating a laser beam either polarized parallel (π pump) or perpendicular (σ pump) to the magnetic field of 6 T. π pump and σ pump dependence of the Zeeman spectra of the Q(K)Q(J=6) lines for K=0–6 was measured. Intensities of the Zeeman components of the Q(6)Q(6) lines were observed to have the maxima at the high and low wave number ends and the minimum at the middle for π pump, and the minima at the high and low wave number ends and the maximum at the middle for σ pump. By comparing calculated and observed patterns of the Zeeman spectra, it became clear that the transition tensor M00 is dominant and the effective intermediate state is 1 1Bu(ππ*). K dependence of the Zeeman spectra of the Q(K)Q(J=15) lines was measured, and the Zeeman splittings were observed to increase proportionally to K2. J dependence of the Zeeman spectra of the Q(K=J)Q(J) lines was measured for J=...

Doppler-free high resolution laser spectroscopies of the naphthalene molecule

Abstract In this work, a variety of techniques, namely Doppler-free polarization labeling spectroscopy, Doppler-free two photon absorption spectroscopy, and laser excitation spectroscopy with reduced Doppler width achieved by crossing a laser beam at right angles to a collimated molecular beam, have been employed to generate fully rotationally resolved spectra of the naphthalene molecule. The A 1 B 1 u (v 8 =1: b 2 g )← X 1 A g (v=0) transition has been investigated by means of Doppler-free laser polarization spectroscopy. This is the first application of this technique to the study of a large polyatomic molecule, and when complemented with an optical–optical double resonance it is demonstrated to be very effective. The A 1 B 1 u (v 4 =1: b 1 u )← X 1 A g (v=0) transition has been recorded by means of two-photon absorption spectroscopy with counter propagating light beams of identical wavelength within an external cavity. Additionally, the effects of an external magnetic field were measured, and the Zeeman splittings were observed to increase with increasing the rotational quantum number J . The Zeeman splittings of the A 1 B 1 u (v 8 =1: b 2 g ,J) levels, which lie 1100 cm −1 below the A 1 B 1 u (v 4 =1: b 1 u ,J) levels, were measured by means of laser excitation spectroscopy by which a laser beam is crossed with a collimated molecular beam. The magnetic moment of the A 1 B 1 u (v 8 =1: b 2 g ,J) level was observed to be smaller than that of the A 1 B 1 u (v 4 =1: b 1 u ,J) level.

Noise-Induced Phase Locking and Frequency Mixing in a Schmitt-Trigger Inverter with Delayed Feedback

We study the synergetic effects in a Schmitt-trigger inverter with a delayed feedback loop subject to both a periodic signal and a white noise. When the frequency of oscillation induced by coherence resonance (CR) approaches that of the external signal enhanced by stochastic resonance (SR) with an increase in the noise intensity of the output, the phase of the former is locked to that of the latter, and the signal-to-noise ratio of the output is enhanced. We further observe the frequency mixing between the SR and CR modes. Such a frequency mixing is also enhanced by optimal noise.

Doppler-free two-photon absorption spectroscopy of trans-glyoxal under magnetic fields up to 6T

In order to measure the Doppler-free two-photon absorption (DFTPA) spectrum in the presence of a strong magnetic field, a sample cell placed in an optical resonator was installed at the centre of the bore of a superconducting magnet capable of generating a magnetic field of up to 6T. Changes in spectra of the A 1Au ← X 1Ag transition of trans-glyoxal were measured as a function of magnetic field strength. Level crossings induced by Zeeman energy shifts were observed. The perturbing level, which shows hyperfine splitting, was identified as the 3Au(nπ*) state, because the hyperfine splitting is small in the 3Bu(ππ*) state and large in the 3Au(nπ*) state. The perturbation between the A 1Au(nπ*) and 3Au(nπ*) states was shown to take place by either vibronic interaction or Zeeman interaction between the 3Au(nπ*) state and the 3Bu(ππ*) component mixed to the A 1Au(nπ*) state by spin-orbit interaction. The magnetic moment of the A 1Au state was determined to be approximately 0.0028μB, and the magnitude of the mixing coefficients ⟨1 3Bu|H so|1 1Au⟩/[E(1 1Au) − E(1 3Bu)] was evaluated to be 0.026.

Correlation spectroscopy with noise light excitation

Abstract Intensity correlation spectroscopy with noise light excitation is studied experimentally and theoretically. Zeeman signals of the ground state of the D 1 transition in Rb atoms were observed. The signals appear in the power and cross spectra obtained from the auto- and cross-correlations of the pump and probe intensities. The frequency resolution is determined by the inverse of the measuring time and is not limited by the spectral width of the light source. A high sensitivity was obtained in the experiment, and a high frequency resolution close to the theoretical limit was achieved. The signal shapes in the Fourier spectra are analyzed by using linear response theory, and the observed signal shapes can well be explained.