State interactions, excitation dynamics, hidden states and photofragmentation pathways in hydrogen halides

The focus of my Ph.D. work is on two separate, but closely related experimental subjects. The first involves the recording of mass resolved two-photon resonance enhanced multiphoton ionization (REMPI) spectra of the hydrogen halides HBr and HI. The REMPI spectra of both molecules reveal extensive perturbation effects; line-shifts, intensity alterations, and line broadenings. These are colloquially referred to as LS-, LI-, and LW-effects, respectively. Measuring these effects quantitatively and qualitatively allows data extraction regarding state interactions (perturbations) between Rydberg and ion-pair states. These interactions include fragmentation via repulsive valence states and subsequent ionization of the fragments. The presence of hidden states is also deduced and they are assigned based on observed perturbation effects. Velocity map imaging (VMI) experiments are performed on HBr. Such experiments measure the angular distributions of photofragmentations and the total kinetic energy release of the imaged fragments. These experiments allow the roles of photofragment channels in the photodissociation and photoionization to be deduced, where Rydberg and ion-pair states act as intermediary states prior to ionization/fragmentation.Þungamiðja doktorsverkefnis míns snerist um tvö aðskilin en náskyld viðfangsefni. Hið fyrra snýst um mælingar á samhrifsstyrktum fjölljóseindajónunar (REMPI) rófum vetnihalíðanna HBr og HI. Skráð róf beggja sameinda leiddu í ljós umtalsverð truflunaráhrif; línuhliðranir, breytingar á línustyrkjum og línuvíkkanir. Þessi áhrif eru til styttingar kölluð LS-, LI- og LW-áhrif. Að mæla þessi áhrif hlutbundið og eigindlega gerir gagnasöfnun varðandi víxlverkanir á milli Rydberg og jónparaástanda mögulega. Þessar víxlverkanir fela m.a. í sér ljóssundrun í gegnum fráhrindandi ástönd og jónun atómbrotanna sem úr þeim myndast. Dulin ástönd eru sömuleiðis fundin í gegnum truflanaáhrif. Hraðavigurskortlagningar (VMI) eru framkvæmdar á HBr. Slíkar tilraunir mæla stefnu og hreyfiorku jónaðra atómbrota. Með niðurstöðum þessara tilrauna má finna hvaða ljósbrotsferlar koma við sögu í ljósrofnunar- og jónunarferlum sameindarinnar þar sem Rydberg og jónparaástönd taka þátt sem miðbiksástönd