Doppler limit

Lett P D, Watts R N, Westbrook C I, Phillips W D, Gould P L and Metcalf H J 1988 Gbservation of atoms, laser-cooled belowthe Doppler limit Phys.Rev.Lett. 61 169-72... 

Dalibard J and Cohen-Tannoudji C 1989 Laser cooling belowthe Doppler limit by polarization gradients simple theoretical models J.Opt.Soc.Am. B 6 2023-45... 

Figure 9.3 Doppler limited laser line with twelve axial modes within the line width...

Figure 9.25 (a) A Doppler-limited line, (b) The detection. V, potential psd, phase-sensitive detector... 

There have been a number of discussions about deconvolving beyond the Doppler limit (see Pliva et al, 1980) but we prefer to go back a step further and simply discuss deconvolving beyond removal of the instrumental spread function. Jansson discusses deconvolving inherent broadening in Section... 

For tunable-diode-laser(TDL) studies where r(x) is much narrower than even a modestly pressure-broadened line, one might either attempt the former method characterized by Eq. (49) or perhaps simply ignore (cautiously) the impact of r(x). From the foregoing discussion, however, it should be obvious that the considerations and potential problems involved in going beyond removal of the effect of r(x) are in no way trivial. Nevertheless, we have successfully deconvolved some data beyond the limit of the removal of r(x). In many instances we have only taken 0.012-cm-1 data for a 0.005-cm 1 Doppler spectrum to. 0.004 cm -1 and have encountered no serious problems. (Quantities refer to FWHM of the peaks.) In other instances, we have deconvolved 0.002-cm-1 TDL spectra of C2H6 at 12 jim to 0.0009 cm-1, which is roughly one-half the Doppler limit. An example is shown in Chapter 7. 

Figures 24 and 25 demonstrate the success of deconvolution beyond the Doppler limit. Trace (a) in both figures is the undeconvolved data and represents the result of signal averaging over a large number of scans to produce a signal-to-noise ratio of approximately 300 1. The spectra were base-line corrected using a 0% absorption corresponding to the apparent base line between lines and a 100% absorption level was assumed, which gave reasonable relative intensities for the range of J values observed. The...

For a lithium beam slowed down to 10 m/s and cooled down close to the Doppler limit (Av/v 0.1), a capacitor 0.5 m long and for ta = Tmax, then ta = 23.5 ms and Tmin=76.5 ms. With the parameters already mentioned one could measure a charge qn as small as the existing limit on the neutron charge qn in about 16 seconds. 

An example for high-resolution IRS is given in Fig. 6.1-26, where the uj 0-branch of CH3D is displayed. This spectrum has been recorded with the quasi-cw inverse Raman spectrometer developed by Bermejo et al. (1990) whose. schematic arrangement is shown in Fig. 3.6-15 and described in Sec. 3.6.2.3. It represents a Doppler-limited spectrum of the C-D stretching band. The authors were able to assign the observed transitions by performing a theoretical fit to the observed data which allowed them to refine some of the rotational-vibrational constants. 

Doppler-free and Doppler-limited fluorescence spectroscopic studies of the He Is2p-ls3d transitions Calculation of electron excitation rate constants for formation of He(ls2s, - S) and He(ls2p, - p ) using evaluated experimental and theoretical data... 

While the early optical measurements suffered from limited resolution, the development of atomic beam methods provided a useful tool in the study of atomic and nuclear magnetic moments [ 12,13] (for a review see [ 14]) and it became possible to measure the nuclear magnetic moments (and nuclear spins) in a direct way for both stable and radioactive isotopes, by using a variety of methods ] 15]. The study of optical IS was, however, limited to Doppler-limited optical spectroscopy until the invention of the laser and the development of suitable high-resolution optical methods (a review can be found in [16]). It is also possible to obtain information on the nuclear charge distribution by electron scattering experiments and from muonic X-ray transitions and electron K X-ray IS [17], perhaps even with a higher accuracy than with optical spectroscopy. 

Tunable diode laser spectroscopy has been employed in order to observe the Zeeman effect in the i.r. absorption of molecules with no electromagnetic moment, due to differences between the excited- and ground-state g-factors. Doppler-limited resolution was obtained for and CHjDI in the region 820—... 

The spectrum of the out-of-plane band of thiophene centered at 712 cm has been measured in Doppler-limited resolution with a diode-laser spectrometer and with a high-resolution FT spectrometer <93ZN(A)1193>. The band at 712 cm which is the Ui, band <65SA689>, is of symmetry Bi. 

In order to estimate the size of the acceptable solid angle of the radiation with which to illuminate an interferometer operating in the visible/UV spectral region, it is necessary to make a few assumptions. We will assume that Doppler-limited resolution is desired over the spectral range from about 7000 A to 3000 A, or in frequency, from about 14,300 cm"l to 33,300 cm"l. It is not likely that this entire bandwidth of 19,000 cm"l would be covered in one spectrum, but it is important to know both the high frequency and low frequency limits when evaluating system performance. 

In Doppler-limited visible/UV spectroscopy, the interferometer is usually the component which determines the overall system throughput. The throughput of the source optics can be designed to match the throughput of the interferometer. If the bean diameter at the beam splitter of the interferometer is D (in cm), then the interferometer throughput at the high frequency limit is... 

The precision with which the optical retardation can be determined is directly related to the frequency stability of the reference source. For Doppler-limited visible/UV spectroscopy, this stability is required to be on the order of one part in Although... 

I will now discuss the work which has been carried out by classical spectroscopy on the electronic spectra of diatomic and polyatomic molecules including unstable chemical species which can be classified as free radicals or molecular ions. More than 1000 diatomic (1) and 100 polyatomic species (2) have been found and studied with Doppler-limited resolution,... 

The instrumental resolution of the spectrometers is limited by the combined frequency fluctuation from each CO2 laser (about 15 kilohertz). This, of course, is less than any Doppler limited linewidth and, therefore, does not limit our resolution except for possible sub-Doppler work. This high resolution provides an excellent way of studying pressure shifts and line shape studies of spectral lines. The measurement of OH concentrations in our atmosphere as a function of altitude using absorption and emission measurements requires an accurate knowledge of its linewidth in the atmosphere. 

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