Picosecond Streak Camera for Measuring Dynamics in Photomechanical Materials
Abstract
Publicly Releasable Project SummaryAgency Program Officer: Peter MorrisonDirectorate: Basic and Applied Sci, Picosecond Streak Camera for Measuring Dynamics in Photomechanical MaterialsPhotons are massless, chargeless particles that can be,beamed across space or directed through optical fibers. They are immune to electromagnetic interference, while possessing control p,arameters (wavelength, polarization) that allow them to be easily manipulated and multiplexed. It is an open question as to whether, photons could supplant chemical fuels and electrons as energy transporters, at least for applications where weight or electromagnet,ic interference are key concerns. To accomplish this, analogs to the internal combustion engine or electric motor must be developed, that can directly convert photons into mechanical work. The PI is a member of a MURI project (Advanced Optical Materials That Cre,ate Force from Light, ONR N00014-18-1-2624) whose goal is to create photomechanical materials that can accomplish the light-to-work, conversion. The general approach is to organize photoreactive molecules in polymers and crystals so that their photoinduced shape,changes can act in concert to generate a macroscopic output. A central goal of the MURI is to gain a quantitative understanding of,how molecular events on picosecond timescales ultimately give rise to largescale photomechanical motion on nanosecond to millisecond, timescales. In order to monitor the material as it evolves chemically and deforms physically, one would like to take snapshots of,both its chemical state and its mechanical actuation.This proposal requests funds to purchase a streak camera that can take such sn,apshots across a range of timescales, from picoseconds to milliseconds. It can be configured for both time-resolved spectral detec,tion and time-resolved position detection, making it the ideal instrument to probe dynamics from molecular to macroscopic lengthscal,es. In its standard configuration, the streak camera can perform time-resolved photoluminescence measurements on stationary samples,, providing information about excited state relaxation rates. The goal of this proposal is to extend the capabilities of this instr,ument and develop new experiments that can address specific questions in photomechanical materials. The three new experiments that,will be based on the streak camera are:1) In conjunction with a pulsed lamp, it will serve as a detector for long-time transient ab,sorption experiments. Combined with a femtosecond set-up, it will allow us to characterize multi-step isomerization reactions over,10 orders of magnitude in time (10-14 s to 10-3 s). 2) It will serve as a high-sensitivity photoluminescence lifetime instrument t,o perform intermittent measurements, allowing us to track changes in material properties and reaction rates during the conversion of, photomechanical crystals and polymers.3) It can be configured to measure the spatial displacements of reacting photomechanical obj,ects with sub-micron resolution across 8 orders of magnitude in time (10-11 s to 10-3 s). We emphasize that all these experiments c,an be performed using the same streak camera detection system. All that is required is to interface it with instrumentation (laser,sources, optical components) already available in the PIs lab. The streak camera will allow us to make concrete connections between, molecular-level chemical reactions and macro-scale mechanical motions. Eventually, these measurements will lead to a unified, mult,iscale understanding of how photomechanical materials transform light into work.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 05, 2022
- Source ID
- N000142212264
Entities
People
- Christopher J Bardeen
Organizations
- Office of Naval Research
- United States Navy
- University of California Regents