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The production of dense samples of atoms whose translational velocity can be parameterized by temperatures in the microkelvin range has revolutionized the fields of spectroscopy, metrology, quantum computing and sensitive tests of quantum mechanics. Such ultracold temperatures may be reached by Doppler cooling which uses a velocitysensitive scattering force. This technique relies upon atoms which have closed electronic transitions between two states so that the atoms may continuously absorb photon momenta and do not spontaneous decay into a dark state. Very few atoms fulfil this condition and attempts to cool molecules are inhibited by their extra degrees of freedom, via rotation and vibration, which add manifolds of extra states. This thesis describes the early experimental stages of investigation into coherent laseratom interactions which may be used as a general all-optical method to impart momentum to atoms and molecules and thus manipulate their velocity. The thesis covers the construction and operation of stable diode lasers, a magneto-optical trap to produce cold samples of the test species Rubidium and a high-power, phase and intensity, controllable laser to induce Raman transitions. Studies into the spectroscopy of Rubidium and the nature of coherent Raman interactions in multilevel atoms is also covered. Experimental results shows that coherent Raman transitions between the 5S1/2 ground states has been achieved in the form of sinc-squared lineshapes and Rabi-flopping. |
