check
Publications | The Banin Research Group

Publications

1993
Uri Banin, Kosloff, Ronnie , and Ruhman, Sanford . 1993. Femtosecond Chemical Dynamics In Solution: Photodissociation Of I3‐. Israel Journal Of Chemistry, 33, 2, Pp. 141-156. . Publisher's Version Abstract

We report a study of the UV photolysis of I3 in alcohol solutions, using femtosecond time‐resolved transient transmission experiments. We interpret our results to indicate that photoexcitation leads to direct formation, within 300 fs, of diiodide ions which are vibrating coherently. The time scales for vibrational dephasing, vibrational relaxation, and reorientation of the fragment ions are 400 fs, 4 ps, and 5 ps, respectively. UV transient transmission experiments were conducted in order to characterize the time scales for recombination. Recombination takes place on several time scales. A fast component is assigned to primary recombination, followed by vibrational relaxation on the ground state of I3. The prominence of this recombination route is found to be strongly dependent on the solvent. Finally, time domain quantum simulation techniques are employed in order to gain insight into the nature of the nascent diiodide vibrational distribution, and to introduce a semiquantitative model for the stage of bond fission for isolated ions.

Uri Banin and Ruhman, Sanford . 1993. Ultrafast Photodissociation Of I3. Coherent Photochemistry In Solution. The Journal Of Chemical Physics, 98, 6, Pp. 4391-4403. . Publisher's Version Abstract

We report a comprehensive study of the UV photolysis of I3 in ethanol solution, using femtosecond time resolved transient transmission experiments. We interpret our results to indicate that with high probability, photoexcitation leads to direct formation of di‐iodide ions within 300 fs, which are vibrating coherently. Through our experiments we have been able to determine that the time scales for vibrational dephasing, vibrational relaxation, and reorientation of the fragment ions are 400 fs, 4 ps, and 5 ps, respectively. Transmission signals at 620 nm and at 880 nm, which are above and below the λmax of the known absorption of I2, oscillate at a precisely opposite phase. This and other results presented indicate that through the oscillations we are observing coherent vibration of the I2 photofragment. UV transient transmission experiments have been conducted in order to characterize the time scales for recombination. Preliminary results show that recombination takes place on several time scales. A fast component is assigned to primary recombination, followed by vibrational relaxation on the ground state of I3. The impulsive nature of the I3 photoexcitation induces coherent symmetric stretching vibration in the ground state tri‐iodide population. Finally, the large number of dynamical variables probed directly allows us to record the chronology of this reaction with unprecedented detail. We directly observe a new and potentially informative dynamical variable for this reaction—the absolute phase of fragment vibrations following the photodissociation.

Uri Banin and Ruhman, Sanford . 1993. Ultrafast Photodissociation Of I3. Coherent Photochemistry In Solution. The Journal Of Chemical Physics, 98, 6, Pp. 4391-4403. . Publisher's Version Abstract

We report a comprehensive study of the UV photolysis of I3 in ethanol solution, using femtosecond time resolved transient transmission experiments. We interpret our results to indicate that with high probability, photoexcitation leads to direct formation of di‐iodide ions within 300 fs, which are vibrating coherently. Through our experiments we have been able to determine that the time scales for vibrational dephasing, vibrational relaxation, and reorientation of the fragment ions are 400 fs, 4 ps, and 5 ps, respectively. Transmission signals at 620 nm and at 880 nm, which are above and below the λmax of the known absorption of I2, oscillate at a precisely opposite phase. This and other results presented indicate that through the oscillations we are observing coherent vibration of the I2 photofragment. UV transient transmission experiments have been conducted in order to characterize the time scales for recombination. Preliminary results show that recombination takes place on several time scales. A fast component is assigned to primary recombination, followed by vibrational relaxation on the ground state of I3. The impulsive nature of the I3 photoexcitation induces coherent symmetric stretching vibration in the ground state tri‐iodide population. Finally, the large number of dynamical variables probed directly allows us to record the chronology of this reaction with unprecedented detail. We directly observe a new and potentially informative dynamical variable for this reaction—the absolute phase of fragment vibrations following the photodissociation.

We report a comprehensive study of the UV photolysis of I3 in ethanol solution, using femtosecond time resolved transient transmission experiments. We interpret our results to indicate that with high probability, photoexcitation leads to direct formation of di‐iodide ions within 300 fs, which are vibrating coherently. Through our experiments we have been able to determine that the time scales for vibrational dephasing, vibrational relaxation, and reorientation of the fragment ions are 400 fs, 4 ps, and 5 ps, respectively. Transmission signals at 620 nm and at 880 nm, which are above and below the λmax of the known absorption of I2, oscillate at a precisely opposite phase. This and other results presented indicate that through the oscillations we are observing coherent vibration of the I2 photofragment. UV transient transmission experiments have been conducted in order to characterize the time scales for recombination. Preliminary results show that recombination takes place on several time scales. A fast component is assigned to primary recombination, followed by vibrational relaxation on the ground state of I3. The impulsive nature of the I3 photoexcitation induces coherent symmetric stretching vibration in the ground state tri‐iodide population. Finally, the large number of dynamical variables probed directly allows us to record the chronology of this reaction with unprecedented detail. We directly observe a new and potentially informative dynamical variable for this reaction—the absolute phase of fragment vibrations following the photodissociation.