Post Tagged with: "upconversion"

ACS LiveSlides: Another Step in Multimedia Science Publishing

Last March I introduced the Hanson research group’s five minute GEOSET videos. I’ve since learned that, in July 2013, Prashant V. Kamat (Deputy Editor), George C. Schatz (Editor-in-Chief) and their co-workers at the Journal of Physical Chemistry Letters announced ACS LiveSlides™, a user friendly mechanism for generating and sharing video slideshows for each manuscript. As noted in their editorial piece, they were motivated by the “changing publication landscape and the wide availability of new electronic tools have made it increasingly important to explore new ways to disseminate published research.”

We recently created an ACS LiveSlides™ presentation for our J. Phys. Chem. Lett. manuscript, “Photon Upconversion and Photocurrent Generation via Self-Assembly at Organic–Inorganic Interfaces.” The paper introduces self-assembled bilayers as a means of facilitating molecular photon upconversion and demonstrates photocurrent generation from the upconverted state. It’s arguably the first example of directly extracting charge from a molecular upconverted state if using the first submission date, first public disclosure, or the patent application date as markers. If using the manuscript acceptance date, Simpson et. al’s publication holds that distinction.

An invitation to create an ACS LiveSlides™ presentation immediately followed the message notifying us that our manuscript was accepted. All we needed to do was provide 5-8 Power Point Slides summarizing the manuscript (using a format provided by the ACS) and record an accompanying <10-minute mp3 audio file. The editors took the files (and a list of times for each slide transitions) and published our LiveSlides™ presentation in less than a week. It was an easy process and now anyone can view our presentation. No subscription necessary.

One drawback is that the video cannot be embedded on a webpage. As stated in their terms:

Files available from the ACS website may be downloaded for personal use only. Users are not otherwise permitted to reproduce, republish, redistribute, or sell any Supporting Information from the ACS website…

So we have a backup plan for those preferring an embedded video. Below you’ll find our GEOSET video summary presented by Sean Hill.

Photo Friday (#picpickoftheweek)

My graduate student, Sean Hill, became the Hanson Research Group twitter account manager last week. We first talked about what is and isn’t acceptable to post on the internet. Then Sean explained to me the nuances of hash tags and how I’ve underutilized them.  He also suggested something brilliant: a photo of the week.

One of the things I like most about doing research in molecular photophysics is the beautiful color chemistry. Now, every Friday, Sean will tweet (#picpickoftheweek) our best photo taken during the prior week. Our first image (below) is very fun and depicts a photon upconversion solution.

Upconversion

This image shows green laser pointer light (532 nm) causing blue (~430 nm) emission from the solution.  What makes this image really interesting, from a photophysics standpoint, is that we’re  observing the conversion of lower energy green photons into higher energy blue photons.

The reverse—higher energy blue light turning into lower energy green light—is easy. Many molecules absorb a single high energy photon and then emit a single lower energy photon with some energy lost in the process due to vibrational relaxation.  The more difficult green-to-blue light change depicted above is only possible if we combine the energy from two green photons to produce one higher energy blue photon.  This process is known as photon upconversion.

While it can be observed in inorganic nanoparticles, the solution above is a mixture of two types of molecules that undergo excitation, energy transfer, triplet-triplet annihilation and then emission.  Our research group is interested in studying these upconversion systems because they could potentially provide a mechanism to harness low energy light and increase the theoretical maximum solar cell efficiency from 33% to >40%. If you’re interested in learning more about photon upconversion through triplet-triplet annihilation, here is a good review article.

Follow us, @HansonFSU, on twitter for more molecular color chemistry.

By January 18, 2014 4 comments fun