Zeeman tuning

Fig. 2. Absorption spectrum of CjHs obtained with the Zeeman-tuned He-Ne laser line at X = 3.39 fim. The dips in the transmission of magnetic field dependent laser intensity are due to different rotational transitions in CjHj, their width is determined by doppler broadening. (From Gerritsen, H.J., ref.

A combination of both methods was realized by Uehara et al. 85,88) They investigated the Stark spectrum of polyatomic molecules in strong electric fields by probing the different Stark components with the Zeeman-tuned laser line. Since the molecular constants of the vibrational ground state are often known from microwave investiga-... 

Fig. 3. Stark modulation spectrum of HDCO around 2850.62 cm", obtained with a Zeeman-tuned Xe laser line at 3.50 fim. The Stark field is perpendicular to the optical field and increases from the bottom towards the top of the figure resulting in an increasing splitting of the Stark levels therefore more and more components are separated. (From Uehara, K.T., Shimizu, T., Shimoda, K., ref. 85))...

The sharpest donor lines reported in natGe are Ap (/l (I I, O) and 4/ i (D (H, O), with FWHMs 6.4 peV (0.05 cm 1). The model of Nishikawa and Barrie [113] has been used by Navarro et al. [109] to compare with the calculated line width the residual width of the 2p line of the D (H, O) donor in ultrapure natGe, measured by Zeeman tuning of the energieer frequencies. The broadening calculated by taking into account the interaction of the 2p 1 level with the four nearest levels (2po, 2s, 3po, and 3s) was 2.5 peV, compared to an experimental value of 8.6 peV for the FWHM of the 2p 1 line, but the calculated value was found to be sensitive to the value of the effective Bohr radius used in the calculation. For the acceptors, the sharpest line reported... 

The medium infrared spectral region contains typically vibrational transitions of molecules and their rotational substructure. Therefore it is obvious, that one can use vibration rotation transitions in a laser medium itself, provided there is an inversion mechanism available. However, in the gas phase such transitions are fairly narrow and therefore will not be the ideal source for spectroscopy, where one would like to have a continuously tunable laser source in order to scan across a series of vibration-rotation transitions of the molecular gas to be investigated. Although we can make use of it for very special situations e.g.for the spectroscopy of paramagnetic molecules, where Zeeman-tuning of the molecular transition can be achieved, we must use other types of gain media for a tunable infrared laser. 

Furthermore, as the atom slows down it would, in the absence of the magnetic field, Doppler tune itself out of resonance with the laser the specially designed solenoid prevents this happening by Zeeman tuning the atoms in synchronism with the velocity reduction i.e., the magnetic field in the direction of travel z of the atoms has the form ... 

The sub-Doppler nature of double resonance with single mode c.w. lasers has been used to resolve hyperfine structure in an infrared-optical study of NH2 (Amano et. al. 1982). A fluorescence cell was placed inside the cavity of a CO2/N2O laser and between the poles of a 15" electromagnet capable of fields up to 22 kG. A dye laser beam was introduced into the cell through a ZnSe mirror, and excited NH2 fluorescence through transitions to levels of the V2 = 9 or 10 states. At magnetic fields which Zeeman tuned into resonance vibration-rotation transitions within the excited state the population transfer changed... 

For the second method, where the laser frequency col is kept constant, the atomic absorption frequency must be altered during the deceleration of the atoms. This can be realized by Zeeman tuning (Fig. 9.7). In order to match the Zeeman shift to the changing Doppler shift Aco(z), the longitudinal magnetic field must have the z-dependence... 

Fig. 9.7 Level diagram for laser cooling by Zeeman tuning...

Fig. 9.8 Laser cooling of atoms in a collimated beam with a fixed laser frequency and Zeeman tuning of the atomic absorption frequency [1125]...

K. Uehara, K. Takagi, T. Kasuya, Stark modulation spectrometer, using a wideband Zeeman-tuned He-Xe laser. Appl. Phys. 24, 187-195 (1981)... 

B. Cahn et al., Zeeman-tuned rotational level crossing spectroscopy in a diatomic free radical. arXiv 1310.6450 [physics]... 

A.C. Luntz, R.G. Brewer, Zeeman-tuned level crossing in S CH4. J. Chem. Phys. 53,3380... 

Historically the Zeeman tuned gas lasers have been the first continuously tunable lasers used in high-resolution molecular spectroscopy [7.15a,b]. The discharge tube of a gas laser is placed in an axial magnetic field which causes a splitting of the gain profiles for the laser transitions into two... 

Fig.7.7. (a) Experimental arrangement of a Zeeman tuned gas laser, (b) Tuned laser spectrogram of CHoF. Upper curve empty cell, lower curve cell filled with CH3F [7.15b]... 

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