RESUMEN
We describe a circuit that acts as an auto-incrementing delay. The circuit allows the user to adjust the total number of delays in a cycle, the incremental delay value, and the amount of time that is spent at each delay step. The circuit is stand-alone, yet is readily interfaced to data acquisition systems. Depending on the delay chip used and the number of steps required, the delay step can be as short as 250 ps or as long as 640 ns. The circuit has been used to control the temporal separation between pulses from independent lasers. This was instrumental in our measurement of population dynamics in an optically excited three-level ladder system.
RESUMEN
We explore 2-color photoassociative ionization in cold Rb vapor and present experimental evidence that the molecular ions are produced from the stepwise excitation of a ladder of molecular states. We also explore a new process, dubbed photoassociative-dissociative ionization, by which atomic ions are created by excitation through a ladder of molecular states, finally autoionizing to a dissociative potential curve of Rb2+. We submit that these experiments could be the starting point for the same sort of high resolution spectroscopy that has already been done for lower electronic states of cold Rb2 at large internuclear separation.
RESUMEN
A modification in the analysis of a conventional laser beam spot size measurement method has been developed. The new analysis significantly decreases the uncertainty in the estimation of the beam-spot size. A conventional beam scanning approach was used in the measurement, but instead of differentiating the data and fitting the result to a Gaussian function, the data were fit to an analytical approximation to the complementary error function. As a result, fitted parameters were obtained that were consistent with the standard differentiation approach, but with considerably smaller uncertainty.
