Observation of Ultrafast Charge Migration in an Amino Acid.
We present the first direct measurement of ultrafast charge migration in a biomolecular building block - the amino acid phenylalanine. Using an extreme ultraviolet pulse of 1.5 fs duration to ionize molecules isolated in the gas phase, the location of the resulting hole was probed by a 6 fs visible/near-infrared pulse. By measuring the yield of a doubly charged ion as a function of the delay between the two pulses, the positive hole was observed to migrate to one end of the cation within 30 fs. This process is likely to originate from even faster coherent charge oscillations in the molecule being dephased by bond stretching which eventually localizes the final position of the charge. This demonstration offers a clear template for observing and controlling this phenomenon in the future.
†Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, BT7 1NN, United Kingdom.
Louise
L
Belshaw
‡Politecnico di Milano, Department of Physics, Institute of Photonics and Nanotechnologies, CNR-IFN, I-20133 Milan, Italy.
Francesca
F
Calegari
†Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, BT7 1NN, United Kingdom.
Martin J
MJ
Duffy
‡Politecnico di Milano, Department of Physics, Institute of Photonics and Nanotechnologies, CNR-IFN, I-20133 Milan, Italy.
Andrea
A
Trabattoni
§Institute of Photonics and Nanotechnologies, CNR-IFN, I-35131 Padua, Italy.
Luca
L
Poletto
‡Politecnico di Milano, Department of Physics, Institute of Photonics and Nanotechnologies, CNR-IFN, I-20133 Milan, Italy.
Mauro
M
Nisoli
†Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, BT7 1NN, United Kingdom.
Jason B
JB
Greenwood
attosecond; charge transfer; intramolecular charge migration; pump−probe; ultrafast