Photoacids as Ultrafast Optical Triggers for Proton Transfer

Photoacids as Ultrafast Optical Triggers for Proton Transfer 

1- naphthol the if], transition has been considered to be the proton transfer rate determining step [56-58]. In contrast, in a recent combined experimental/theoretical study of pyranine (8-hydroxy-l,3,6-trisulfonate-pyrene HPTS) [59-61] it has been concluded that the rate determining step in the excited state proton dissociation reaction is not the conversion from the optically accessible locally excited (LE) state (resembling the properties of the L],-state of naphthalene) to the electronically excited CT state (resembling the iL -state character of naphthalene), but the transition of the photoacid CT to photobase CT states. 

2- amino-pyridine clusters [68]. Net proton transfer on the other hand should 

Recently, the excited state characteristics of HPTS have been probed with mid-infrared pulses providing insight into state-specific vibrational modes [76]. In Fig. 14.3 the absorbance changes in the fingerprint region of HPTS are shown to be solvent dependent. The fact that these vibrational band patterns appear within the time resolution of 150 fs, without any additional changes up to several tens of picoseconds, indicates that previous observations of a 2.5 ps time component in UV/vis pump-probe experiments [59, 60] previously assigned to a iL], — level 

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