Doppler doublet

The molecular expansion travels parallel to the microwave cavity axis and, as a result, the observed transitions are split into Doppler doublets at sufficient resolution. Typical linewidths are 10 kHz and depend on the observation time, that is, the time required for the beam to travel from the nozzle to the opposite mirror. This in turn depends on the mirror separation and the backing gas (typically He, Ne, or Ar) used. 

Figure 2 Spectrum of the J = 8-7 rotational transition of I32xe65cu35ci xiig complicated hyperfine structure arises from nuclear quadrupole interactions of Cu (7cu = 3/2) and Cl (Id = 3/2). All transitions are split into Doppler doublets as a result of the molecular expansion traveling parallel to the microwave cavity axis. For clarity of the picture, the quantum number assignments of only a few hyperfine components are given as F -F". The...

Figure 2 Spectrum of the 7 = 8-7 rotational transition of Xe Cu Cl. The compUcated hyperfine structure arises from nuclear quadrupole interactions of Cu (7cu = 3/2) and C1 (7qi = 3/2). All transitions are spUt into Doppler doublets as a result of the molecular expansion traveling parallel to the microwave cavity axis. For clarity of the picture, the quantum number assignments of only a few hyperfine components are given as Fj -F/, F -F". The angular momentum coupling scheme Fi = Icu + J F = Fi + Iq was used. The compound was produced using laser ablation of a copper rod in a molecular expansion of a mixture of 0.1% CI2, 15% Xe, and 85% Ar. The particular isotopomer was measured in its natural abundance of 6.3%. This spectmm was recorded using 15 000 averaging cycles with a total accumulation time of about 3.5 h...

Figure 4 A 172 MHz broad-band scan (lower trace) and high-resolution spectrum (upper trace) of phenol and water in helium at a stagnation pressure of 100 kPa. Three lines can be recognized in the low-resolution spectrum a doublet consisting of a strong and a weak component of the 6oe

Fig. 6. Doppler profile of H and D fragments from the photolysis of C2H2 and C2D2, respectively. The narrow doublet at the center is the Doppler profile of a supersonically-cooled H-atom beam.

Cases have been observed where the isotopic line absorption profiles completely overlap, e.g. boron-10 and -11 in a krypton-filled lamp at 249.7 nm [244]. Hannaford and Lowe [245] later showed that this was caused by an unusually large Doppler half-width induced by the fill-gas, and, if neon is used, the 208.9 and 209.0 nm lines can allow the determination of boron-10 and boron-11 isotope ratios. The 208.89/208.96 nm doublet was found to be more useful than the 249.68/249.77 nm doublet. Enriched isotope hollow-cathode lamps were used as sources. A sputtering cell was preferred to a nitrous oxide/acetylene flame as the atom reservoir, as it could be water-cooled to reduce broadening and solid samples could be used, thus avoiding the slow dissolution in nitric acid of samples of boron-10 used as a neutron absorber in reactor technology. 

An clastic wave propagates with the velocity V, and Doppler s shift in frequency must occur. Of all possible directions of elastic waves, only two meet condition 17 those which propagate along two opposite directions with the velocities +V and - V, so the spectrum of scattered light is split into Mandelshtam-Drillouin s doublet (Fabelinski, 1965 Kerker, 1969 Vuks, 1977)... 

In the QCYK spectrum, there are a number of potential problems due to the close proximity of extraneous peaks to those to be measured. Particularly difficult is the measurement of the 514.00 keV peak of Sr in the presence of the 511.00keV annihilation peak. Unfortunately, most commercial software does not recognize the fact that the annihilation peak is Doppler broadened and deconvolution of the doublet may be questionable. A similar problem could arise when measuring the 1332.49 keV peak of Co in the presence of the 1325.05 keV single escape peak of which will also be broadened. Fortunately, on any reasonable detector deconvolution will not be necessary. Attention can be drawn to the fact that the energy of the single escape peak of the Co 1173.23 keV peak, 662.23 keV, is very close to the 661.66 keV peak of Cs, although the intensity is very low and there is no problem in practice. 

Fig. 25 (a) The 4j 4-3q,3 rotational transition of thymine showing the N quadrupole components labeled with the quantum numbers f I". (b) Detail of the 7,f = 2,4<—2,3 quadrupole component, which is split into four lines because of the internal rotation (A-E doublet) and Doppler effects ([-]). (From [167])... 

The electric quadmpole spfitting gives information on the oxidation state, the spin state and the local symmetry of the Mossbauer atom. Note that the isomer shift parameter 6 is given by the distance of the barycenter of the quadmpole doublet from zero Doppler velocity (Fig. 2.4). 

Doppler-resolved laser-induced fluorescence of nascent products of inelastic collisions, reaction or photodissociation [33], as well as lambda doublet and fine structure analysis of such products as OH and CN radicals [34]. There is a preponderance of studies of bimolecular reactions involving excited reagents (sometimes as a function of collision energy), e.g. the elementary reactions... 

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