Doppler spectroscopy method

V. V. Vlasenko. Studies on photo-sensitivity of unicellular moving micro-algae by method Doppler spectroscopy, Reports of the National Academy of Sciences of Ukraine 11, 172-178 (2004). 

An optical technique involving Doppler spectroscopy can also serve to gain insight into the angular and velocity distributions of reaction products, as reviewed in Ref. [43]. Finally, the Doppler method has been associated with the imaging technique. This is the so-called Doppler-selected time-of-flight technique, which is the most powerful one to obtain information on the three-dimensional (3D) velocity and angular distribution of the reaction products [44-46]. 

We will now consider different laser spectroscopy methods. We will first discuss techniques in which a reasonable resolution is sufficient and where relatively broad-band lasers (0.1-0.01 A) and Doppler-broadened samples are used. We will then describe how resonance techniques can be combined with laser excitation. In the following sections, time-resolved spectroscopy will be considered. Lifetime measurements and structure determinations using such techniques will be described. In this context a comprehensive survey of methods for determining the radiative properties of atoms and molecules is made. 

We will now consider different laser spectroscopy methods. We will first discuss techniques in which a reasonable resolution is suflScient and where relatively broadband lasers (0.01—0.001 nm) and Doppler-broadened samples... 

Various techniques of sensitive absorption spectroscopy, including nonlinear techniques, which allow a spectral resolution below the Doppler width are described first. These techniques are termed sub-Doppler-spectroscopy and include linear spectroscopy in collimated molecular beams, nonlinear saturation and polarization spectroscopy, and Doppler-free two-photon spectroscopy. Emission spectroscopy, which covers laser-induced fluorescence as well as stimulated emission methods, is described next. The assignment of complex molecular... 

Perhaps even more than other fields of application in laser spectroscopy, ion physics is likely to benefit rapidly from progress in the U.V. range. Frequency doubled CW gas and dye lasers are now able to provide on a routine basis the few milliwatts of monomode laser power which have been necessary for the N20" photodissociation experiment. Further in the U.V., the Doppler tuning method could take advantage with much benefit of the high spectral brightness of injected excimer amplifiers operated at high repetition rate. 

Two-photon spectroscopy was introduced as a first-order Doppler-free method by Vasilenko et al. in 1970 and has since been developed into a versatile tool in high-resolution spectroscopy on thermal absorbers. The main attraction in two-photon absorption (TPA), besides the high resolution, is the possibility to induce transitions between levels with the same parity. Hydrogen Is - 2s and positron-ium 1 3S - 2 are two prominent cases of fundamental interest. 

Thus, multiphoton absorption spectroscopy supplements one-photon spectroscopy and allows one to observe transitions between states with the same parity, which are forbidden for one-photon transitions, to form highly excited states of molecules using the visible frequency range, to perform spectrally more resolved intra-Doppler spectroscopy, and to perform multiphoton ionization, which is used in mass spectroscopic and other ionization methods of detection of active species. 

Methods for analysis of the particle size distribution in the aerosol cloud include techniques such as time of flight measurement (TOE), inertial impaction and laser diffraction. Dynamic light scattering (photon correlation spectroscopy) is confined to particles (in suspension) in the submicron range. In addition to the size distribution, the particle velocity distribution can be measured with the Phase Doppler technique. 

The methods of Doppler-free two-photon laser spectroscopy allow very precise comparison of the frequencies of the IS — 2S transitions in hydrogen and deuterium. The frequency difference... 

Mossbauer spectroscopy, also called recoil-free nuclear resonance absorption, depends upon resonant absorption of y-rays emitted by a radioactive source by atomic nuclei.120 The phenomenon was initially difficult to observe, but the German physicist Mossbauer devised a way in which to record the absorption of a quantum of energy equal to the difference in two energy states of the atomic nucleus. The method depends upon a Doppler effect observed when the sample or source moves. Consequently, Mossbauer spectra, such as that in Fig. 16-18, are plots of absorp-... 

The methods described in this book are primarily concerned with the measurement of the microstructure of complex fluids subject to the application of external, orienting fields. In the case of flow, it is also of interest to measure the kinematics of the fluid motion. This chapter describes two experimental techniques that can be used for this purpose laser Doppler velocimetry for the measurement of fluid velocities, and dynamic light scattering (or photon correlation spectroscopy) for the determination of velocity gradients. 

Abstract. This paper deals with high resolution spectroscopy of hydrogen and deuterium atoms. The 1S-3S and 2S-6S/D transitions have been used to determine the ground state Lamb shift with an accuracy of 46 kHz. The aim of the present experiment is to make an absolute frequency measurement of the 1S-3S transition. We present in this paper the improvement on the experiment and the developpment of a new method to compensate the second order Doppler effect by the application of a magnetic field. 

The still necessary increase in accuracy requires an additional effort. A simultaneous spectroscopy of pionic and muonic hydrogen atoms is planned as the muonic X-rays do not show any strong interaction broadening, but exhibit Doppler broadening similar to pionic atoms. A method was found to measure pionic and muonic X-rays simultaneously. The reduced masses of pionic and muonic hydrogen exhibit almost the same ratio as two lattice plane differences of quartz. With a two crystal set up the pionic and muonic X-rays can be Bragg reflected to the same CCD detector. 

Most precision spectroscopy of medium Z ions has been conducted at accelerators or tokamak plasmas, but the recent development of the electron beam ion trap (EBIT) has offered a new spectroscopic source to experimenters. Our experimental method takes advantage of the Doppler free and relatively clean spectra produced by an EBIT and is coupled with an external calibration source to allow absolute measurement of highly charged ions. These are the first precision X-ray measurements conducted at the NIST EBIT [12],... 

The method we use is Doppler free two-photon laser spectroscopy, applied to the atomic hydrogen transitions from the metastable 2S state to the Rydberg nD states (n = 8, 10, 12) /8/. 

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