First, a brief overview of our laser systems. At last count we have 12 Nd:YAG lasers, 6 dye lasers, and 3 solid state optical parametric oscillators (OPOs). Of our YAGs, we have 2 Continuum Minilite II's, 1 Continuum 661, 4 Continuum 7000's, 1 Continuum 7020, 1 Continuum 8000, and 2 Innolas SL600. Our last YAG is integrated into a ScanmatePro dye laser from Lamda Physik. Our remaining 5 dye lasers include a Lamda Physik LPD 3000, 2 Lamda Physik Scanmates, and 2 Radiant Dyes NarrowScans. All of our dye lasers include the capability to double the frequency of the output from the dye laser. Our three solid state OPO's are from LaserVision and include 2 IR OPO/OPA's and 1 UV OPO.

These laser systems provide us with the ability to cover several important regions of the electromagnetic spectrum. Each YAG is capable of producing high power sub 10 nanosecond long pulses (actual pulse length varies with each laser and whether or not a seeder is used) at 1064 nm. The fundamental of the YAG is most often frequency doubled to 532 nm, although other harmonics used are 355 nm and 266 nm. When the YAG is used to pump dye lasers, we are able to produce tunable visible laser light in the region 390-800 nm. In order to be useful for probing electronic transitions in molecules (that contain aromatic chromophores) we need ultraviolet light. As mentioned above, this is achieved by frequency doubling the visible output of the dye lasers, giving us tunable laser light in the region 200-400 nm, where most aromatic molecules have their first electronic transitions. In photochemistry experiments, we sometimes need to go even further into the ultraviolet. The 355 nm output of a YAG can be sent into a tube containing argon and xenon, tripling the frequency to 118 nm, giving us light with enough energy to ionize most of the types of molecules we study. The YAG-pumped UV OPO system is also capable of producing light throughout the visible and ultraviolet regions.

In most cases, electronic spectroscopy does not yield enough information about our molecules to provide us with the answers we seek. Therefore, we also work in the infrared. Two of our YAGs are devoted to pumping IR OPOs which produce light in the regions 725-835 nm and 5000-6700 cm^-1 (where we can look at hydride stretch overtones) in the OPO stage and 2400-4200 cm^-1 (where many hydride stretches appear) in the OPA stage. More recently in our lab we've been able to extend our reach into the infrared by using a AgGaSe₂ crystal to produce light down to 1000 cm^-1.