Ground state transitions, microwave measurement

Abstract. Following a suggestion of Kostelecky et al. we have evaluated a test of CPT and Lorentz invariance from the microwave spectrosopy of muonium. Precise measurements have been reported for the transition frequencies U12 and 1/34 for ground state muonium in a magnetic field H of 1.7 T, both of which involve principally muon spin flip. These frequencies depend on both the hyperfine interaction and Zeeman effect. Hamiltonian terms beyond the standard model which violate CPT and Lorentz invariance would contribute shifts <5 12 and <5 34. The nonstandard theory indicates that P12 and 34 should oscillate with the earth s sidereal frequency and that 5v 2 and <5 34 would be anticorrelated. We find no time dependence in m2 — vza at the level of 20 Hz, which is used to set an upper limit on the size of CPT and Lorentz violating parameters. 

BaO was produced by allowing barium vapour in an argon carrier to interact with traces of oxygen. Microwave power was introduced by means of a simple horn situated close to the optical interaction zone. By tuning the dye laser frequency to coincide exclusively with a succession of rovibronic transitions, it was possible to observe and measure four rotational transitions in the X 1 + ground state, involving both v = 0 and v = 1, and thirteen rotational transitions in the A 1 X excited electronic state. From these measurements accurate values of the rotational constants were obtained, particularly for the excited state. 

TiN has an X 2S+ ground state and rotational transitions in the v = 0 level have been measured and analysed [69, 70] pure millimetre wave and microwave/optical double resonance methods were used, over a frequency range from 37 to 446 GHz. 14N hyperfrne structure was observed for the two lowest rotational transitions, and the spectrum analysed using the conventional effective Hamiltonian, again expressed in cartesian form ... 

Fig. 5 Magnetization curves measured on Peg in the presence of microwave radiation with V = 118 GHz and 7 = 10 K. The dips are due to transitions between the Ms states of the S = 10 ground state, as indicated. Adapted from [115]. Used with permission. 2005 American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modified, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society...

An example of a quantitatively-analysed experimental result for these constants is shown in Fig. 7.29 in mixed crystals of naphthalene-dg 0.1% quinoxaline, the ESR transition T. To for the field direction Bo Xquinoxaiine and at a temperature T = 1.8 K is an absorption signal in the stationary state (Fig. 7.29a), while the transition I To) T-) in the stationary state exhibits stimulated emission of microwaves (Fig. 7.29b). After the end of the UV excitation at t = 0, the absorption line temporarily becomes an emission tine and vice versa. The interpretation of these results is simple (Fig. 7.29d) due to the negligible spin-lattice relaxation at T= 1.8 K, the three Zeeman components decay after the end of the U V excitation independently of one another, each with its own lifetime tj = into the So ground state. Since the difference of the populations of the three states is directly proportional to the intensity of the ESR signals, their time dependence can be used to determine the individual lifetimes of the Zeeman components involved. In the case of the particular orientation Boll, the state is To) = IT ), and one obtains directly from the measurements, e.g. the decay constant feo = kx and thus the lifetime of the zero-field constant Tx) of quinoxaline. 

A number of halogenomethanes have been subjected to other forms of molecular spectroscopy. High-resolution Stark spectra of several transitions of the V3 band of CH3F have been studied by means of a CO2 laser measurements of the hyperfine structure on certain rotational transitions in CH2F2 have been made using a molecular beam maser spectrometer the millimetre-wave spectrum of ground-state CDCla and the microwave spectrum of CD3I in excited vibrational states have also been observed. 

The constants in Table 6 were determined [4,5,6] by using the very precise microwave and submillimeter-wave data [1,8, 19 to 22] (see Table 14, p. 185) and by combining these data with data of rotational transitions in the far IR [4] and with ground-state combination differences from high-resolution measurements of the Vg band of PH3 [5]. Similarly detailed rotational analyses are given in [4, 12]. 

A new very sensitive and accurate double-resonance technique is the Microwave-Optical double-resonance Polarization Spectroscopy (MOPS) developed by Ernst et. al [10.93]. This technique detects microwave transitions in a sample between crossed polarizers through the change in transmission of a polarized optical wave. The sensitivity of the method has been demonstrated by measurements of the hfs of rotational transitions in the electronic ground state of CaCl molecules which were produced by the reaction 2Ca+ CI2 - CaCl in an argon flow. In spite of the small concentrations of CaCl reaction products and the short absorption pathlength in the reaction zone a good signal-to-noise ratio could be achieved at linewidths of lf2 MHz [10.94]. 

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