Optical studies using tunable solid state lasers

This thesis describes laser systems based on Ti:sapphire and their application to precise, Doppler-free, laser spectroscopy of muonium, and to optical pumping in atomic thallium. The optical pumping experiment is a preliminary one to assess the viability of an EDM (electric dipole moment) test in atomic thallium; this is related to T- and P-violation in physics. The resonance transition at 377 nm (6P_1_/_2 #-># 7S_1_/_2) is optically excited using polarized laser light to produce a population imbalance in the magnetic sub-states of the 6P_1_/_2 ground state. Radio-frequency transitions between these Zeeman states are then investigated in an steady magnetic field under a variety of experimental conditions. Some theoretical modelling is included to describe the various complicating effects, including the presence of trapped population in the 6P_3_/_2 state. The minimum observed r.f. linewidth is 30 kHz, which is probably too large for a sensitive EDM measurement. The laser system developed for this experiment is a frequency-doubled, Th:sapphire laser using a non-linear crystal of LBO (lithium tri-borate) which is capable of an output power of 20 mW with a linewidth #<=#1 MHz in the 360-400 nm region. This blue-UV laser system was also used for Doppler-free spectroscopy of the caesium 6S_1_/_2 #-># 8P_1_/_2_,_3_/_2 transitions. We have observed a narrow linewidth of 4.5 MHz using a 1 m long cell. A frequency gap of 79 123.4(5) MHz between the caesium 6S_1_/_2(F = 4) #-># 8P_1_/_2(F = 3) transition (in the fundamental) and the rubidium ("8"7Rb) 5S_1_/_2(F = 2) #-># 5D_5_/_2(F = 4) hyperfine component has been measured using an interferometric method, giving the absolute frequency of this caesium transition to be 770 727 379.5(10) MHz. We propose this transition as a secondary frequency standard in near UV. High resolution laser spectroscopy of 1S-2S transition in the muonium (#mu#"+e"-) provides a clean test of QED (quantum electrodynamics), and promises a new measurement of the muon mass. The laser system used in this experiment includes a cw, Ti:sapphire laser, a high power, pulsed, alexandrite laser, and a frequency tripling system (LBO+BBO). The Ti:sapphire laser was stabilized to a molecular iodine hyperfine transition, as a secondary frequency standard, using FM spectroscopy. The absolute frequencies of the molecular iodine transitions used have been calibrated to an uncertainty 140 kHz at the NPL (National Physical Laboratory). Another candidate, the two-photon transition in potassium (4S_1_/_2 #-># 6S_1_/_2) is also reported here for the first time. The 244 nm, UV pulse 'generated using frequency tripling' interacted with muonium produced using the pulsed surface muon facility at RAL (Rutherford Appleton Laboratory). When the laser frequency was tuned to the muonium 1S-2S two-photon transition, photo-ionization could occur with a third photon from the same laser field. The released muon was detected using a MCP (micro-channel plate). With 34 hours of running time, we obtained the following result for the muonium 1S_1_/_2(F = 1) #-># 2S_1_/_2 (F = 1) transition: #DELTA##nu#_1_S_2_S = 2 455 528 940.99 (9.12)(3.5) MHz where the first errors presents the statistical and the second term systematical. The uncertainty of our measurement gives improvement of a factor of 5, compared with previous experiments. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:D203886 / BLDSC - British Library Document Supply CentreGBUnited Kingdo