Research highlights potential for improved s...(n carrier multiplication research have b...)

Date:2/10/2009

n carrier multiplication research have become contentious. Specifically, some recent studies described low or negligible carrier multiplication efficiencies, which seemed to run contrary to earlier findings. To sort out these discrepancies, Los Alamos researchers analyzed factors that could have led to a spread in the reported carrier multiplication results. These factors included variations between samples, differences in detection techniques, and effects mimicking the signatures of carrier multiplication in spectroscopic measurements.

To analyze how a particular detection technique might affect an outcome, John McGuire, a postdoctoral researcher on Klimov's team, investigated carrier multiplication using two different spectroscopic techniquestransient absorption and time-resolved photoluminescence. The results obtained by these two methods were in remarkable agreement, indicating that the use of different detection techniques is unlikely to explain discrepancies highlighted by other researchers. Further, although these measurements revealed some sample-to-sample variation in carrier multiplication yields, these variations were much smaller than the spread in reported data.

After ruling out these two potential causes of discrepancies, the researchers focused on effects that could mimic carrier multiplication. One such effect is photoionization of nanocrystals.

"When a nanocrystal absorbs a high-energy photon, an electron can acquire enough energy to escape the material," Klimov explained. "This leaves behind a charged nanocrystal, which contains a positive 'hole.' Photogeneration of another electron by a second photon results in a two-hole, one-electron state, reminiscent of one produced by carrier multiplication, which can lead to false positives," he said.

To evaluate the influence of photoionization, the Los Alamos researchers conducted back-to-back studies of static and stirred solutions of nanocrystals. Stirring removes cha
'/>"/>

Contact: James E. Rickman jamesr@lanl.gov 505-665-9203 DOE/Los Alamos National Laboratory Source:Eurekalert

1 GOOD

Page: 1 2 3
Related biology technology :

1. Research Triangle Area Health Care Collaborative Launches Bridges to Excellence(R) Initiative to Improve Quality and Lower Costs
2. The Multiple Myeloma Research Consortium (MMRC) and Proteolix Initiate Phase 2 Clinical Trial Investigating Carfilzomib for the Treatment of Multiple Myeloma
3. BioMarin Licenses Technology From Leading Cystic Fibrosis Research Laboratory at the University of California, San Francisco
4. IDM Pharma Names Dr. Jeffrey W. Sherman Chief Medical Officer and Senior Vice President of Research and Development
5. Dawson James Securities Initiates Research Coverage on CryoCor, Inc. (Nasdaq: CRYO) with a Strong Buy Rating and $6.00 Target Price
6. eResearchTechnology to Present at the Thomas Weisel Healthcare Conference 2007 on September 5th
7. The Debiopharm Life Sciences Award Goes to Dr Nusser for his Outstanding Research in Neuroscience
8. Study Published in Clinical Cancer Research Confirms Potential Of Peregrines Bavituximab Combined With Radiation In Lung Cancer
9. Dow AgroSciences and Exelixis Plant Sciences Announce Major Research Collaboration, Asset Purchase to Advance Gene Discovery and Validation
10. Revolutionary Genomics Research Group Opens Boston Office; Provides DNA Evidence in Workers Comp Cases
11. Richard Schulz Receives the Coveted GCPj Award for Best Clinical Researcher of the Year