Fluorescence lifetime measurements with PicoQuant systems
My team is conducting a partnership with PicoQuant GmbH for fluorescence lifetime measurements with time-correlated single photon counting.
As a brief summary, we operate the following PicoQuant devices :
- LDH-P-635 picosecond laser diode working at 636 nm (special spectral selection has been set for free) + Laser diode driver SEPIA-II-SLM828
- Micro Photon Devices MPD-5CTC fast avalanche photodiode, with timing jitter about 50 ps and active area 50 μm
- PicoHarp 300 fast TCSPC module (resolution per channel 4 ps)
Overall, the best temporal resolution of our setup is 120 ps FWHM. We’re pretty pleased with that materials.
Once you get accustomed to TCSPC concepts (which may be a bit tricky at the beginning), the use of PicoQuant systems is very intuitive and efficient.
Microsphere-enhanced single molecule fluorescence
Our latest paper has been published in the July issue of the Journal of the Optical Society of America B. Free reprints for personal use only are available on our group website here.
In this manuscript, we investigate the interaction between a dipolar emitter and a dielectric microsphere under focused laser illumination. We present a detailed experimental analysis of the fluorescence emission characteristics, and relate our observations to numerical simulations.
Our findings demonstrate that the microsphere acts as a microlens placed in the emitter's near-field, allowing a more efficient focusing of the incident beam as well as increasing the collection of the fluorescence light up to 60% of the total emission. That last figure is more than all the emission normally emitted in the half-space towards the detectors.
This simple scheme outperforms the classical diffraction-limited detection of fluorescent particles, and opens new opportunities for low-cost and highly parallel single-molecule investigations.
Krabi autrement
In a rush of setting up a new house together with a new experiment, I somehow passed aside writing a few words here about Mark Leger, a.k.a Krabi Autrement.
Mark is a French-Thai free-lance guide for people wishing to discover the Krabi province of Thailand in an unconventional manner. I met him for ten days last February, and the least I can say is that I warmly recommend him.
Learn more on his website : www.krabiautrement.com
This is what I wrote about him in his webpage :
"Si vous en arrivez à lire ce texte, et qu'au fond de vous vous sentez une affinité pour la démarche entamée par Mark, alors n'hésitez plus, Krabi-autrement est fait pour vous. Mark est très disponible et à l'écoute de vos attentes. Il sait aussi bien se faire très discret, et respecter votre rythme. Ces qualités, associées à un grand professionnalisme et une profonde gentillesse, font sans doute de lui le meilleur guide francophone de cette région magnifique.
Votre seul prérequis sera de vouloir être vous-même un acteur central de votre voyage. Mark vous fera découvrir énormément de choses et s'occupera volontiers de la logistique. Vous pourrez donc vous concentrer sur l'essentiel : la curiosité de vous ouvrir à cette partie du monde. Et elle le vous rendra bien. On dit de Krabi qu'elle est la plus belle province de Thaïlande. Ce qui est certain, c'est qu'elle est fascinante."
OMNT June selection
If you visit this blog, the following articles may be of interest to you, these are my recent papers selection for the OMNT :
"Engineered SERS Substrates with Multiscale Signal Enhancement: Nanoparticle Cluster Arrays", B. Yan, A. Thubagere, R. Premasiri, L. D. Ziegler, L. Dal Negro, and B. Reinhard, ACS Nano 3, 1190-1202 (2009).
"Label-Free Biomedical Imaging with High Sensitivity by Stimulated Raman Scattering Microscopy", Christian W. Freudiger, Wei Min, Brian G. Saar, Sijia Lu, Gary R. Holtom, Chengwei He, Jason C. Tsai, Jing X. Kang, X. Sunney Xie, Science 322, 1857-1861 (2008).
Nanoapertures for biophotonics
Published in the International Journal of Materials and Product Technology, in a special issue on nanostructured materials for photonics applications :
Biophotonics applications of nanometric apertures
Jerome Wenger, Davy Gerard, Pierre-Francois Lenne, Herve Rigneault, Nicolas Bonod, Evgeny Popov, Didier Marguet, Constantin Nelep, Thomas W. Ebbesen
DOI: 10.1504/IJMPT.2009.025002
Actually, this paper was written in March 2007, revised version accepted for publication in September 2007, and finally published in April 2009 !! Never got a decent explanation with such a delay. So this explains why the reference list therein is mostly already obsolete now, with no citations to papers of late 2007 and 2008.
For personal use only, free reprints are available here.
