Visible vibrational-electronic spectroscopy of molecular iodine vapor is frequently studied in undergraduate physical chemistry teaching laboratories, but limited access to effective instrumentation for producing emission data has been a drawback for many instructors seeking to implement this exercise. This presentation will show that inexpensive green diode-pumped solid-state (DPSS) lasers together with miniature fiber-optic spectrometers to record the rotationally resolved emission should now enable most institutions to adopt an experiment on fluorescence spectroscopy of I2. Simple, user-friendly instruments including single- and multi-mode laser devices operating at 532 nm, CCD array spectrometers having 1.5 nm or 0.15 nm resolution, and ancillary optical diagnostic equipment will be described and compared. Fluorescence bands up to v' = 42 near 900 nm can be observed with acquisition times of less than one minute. Some green DPSS lasers can be actively tuned to excite a single ro-vibronic level in the B state, which allows measured fluorescence transitions to be converted into band origin values before fitting vibrational constants. Approaches to combining fluorescence and absorption data for analysis of the ground and excited electronic states will be discussed. 

Fluorescence spectroscopy of molecular iodine using diode-pumped solid-state lasers

246th National Meeting (2013)

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