Electrospray photodetachment photoelectron spectroscopy

Here we present the results of P3 studies of the VDEs of the most stable conformation of a dinucleotide—2, 2 -deoxyribodithymidine-3, 5 -monophosphate anion (dDTMP- or dTT-). The choice of this particular dinucleotide was dictated by (1) the availability of electrospray photodetachment photoelectron spectroscopy data, (2) the relatively small size of dTT-, and (3) the lack of tautomeric transitions in the parent nucleobase, thymine. The structure depicted in Figure 1 seems to be a global minimum. It was found among numerous conformations of dTT- by means of, first, molecular mechanics analysis and, second, reoptimization of the structures with the B3LYP/ 6-311 + + G model. The structure shown in Figure 1 is characterized by two H bonds between one of the phosphate oxygens and the two... 

Electron detachment from anionic mono-, di-, and trinucleotides was studied experimentally by electrospray photodetachment photoelectron spectroscopy (EPPS) [74]. Substrates did not decompose at the relatively low temperatures of these experiments. 

The electronic structure of several model complexes for mononuclear iron proteins has been evaluated by gas-phase photodetachment photoelectron spectroscopy. Molecules of interest are negatively charged, such as Fe(SCN)3, Fe(SCN)4, and Fe(SCN)4. The anions were transported into the gas phase by electrospray ionization isolated Fe(SCN)4 was not detected in the gas phase, but rather was trapped as the stabilized ion pair Na+ [Fe(SCN)4 ]. 

In a parallel effort, Wang and co-workers added a cold Paul trap to their electrospray ion source and used it for photoelectron spectroscopy of buffer-gas cooled anions [117, 118]. In this case, spectroscopic detection is achieved by collecting the photodetached electrons. While the trap could be cooled to 10 K, it is difficult to determine absolute ion temperatures because photoelectron spectra are inherently broader than IR or UV absorption spectra, preventing the resolution of low frequency hot bands. Although their focus was primarily on non-biological cluster ions of various types, elements of their machine design were later applied to the spectroscopy of biological ions [119]. 

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