Publications by authors named "Logan R Chieffo"
We report the demonstration of optical compression of an electron beam and the production of controllable trains of femtosecond, soft x-ray pulses with the Linac Coherent Light Source (LCLS) free-electron laser (FEL). This is achieved by enhanced self-amplified spontaneous emission with a 2 μm laser and a dechirper device. Optical compression was achieved by modulating the energy of an electron beam with the laser and then compressing with a chicane, resulting in high current spikes on the beam which we observe to lase.
View Article and Find Full Text PDFUltrafast infrared spectroscopy of N 2O is shown to be a sensitive probe of hydrophobic and aqueous sites in lipid bilayers. Distinct rates of VER of the nu 3 antisymmetric stretching mode of N 2O can be distinguished for N 2O solvated in the acyl tail, interfacial water, and bulk water regions of hydrated dioleoylphosphatidylcholine (DOPC) bilayers. The lifetime of the interfacial N 2O population is hydration-dependent.
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- Recent studies indicate that photoactive proteins can quickly respond to light, with some reactions occurring in just picoseconds; this is especially true in proteins like rhodopsin, where changes in structure may be triggered by retinal isomerization.
- The research examines early structural changes in proteorhodopsin (PR) using advanced ultrafast transient infrared spectroscopy, revealing significant vibrational changes after photoexcitation, including isomerization of the chromophore within 500-700 femtoseconds.
- Findings suggest that specific peptide backbone groups in PR may also respond almost simultaneously with chromophore changes, potentially playing a role in energy storage for proton transport.