Determination of subyoctomole amounts of nonfluorescent molecules using a thermal lens microscope: Subsingle-molecule determination

M. Tokeshi, M. Uchida, A. Hibara, T. Sawada, T. Kitamori

Research output: Contribution to journalArticle

181 Citations (Scopus)

Abstract

The photothermal effect of an ultratrace amount of non-fluorescent molecules in liquid was determined by optimizing the optical arrangement for a thermal lens microscope. The optimized experimental setup could be determined from the evaluation of probing volume and the concentration of the sample solutions even when the expectation of the molecule number in the probing region was less than a single molecule. The minimum expectation, which is explained as being the time average, was 0.4 molecule of Pb(II) octaethylporphyrin (OEP) in benzene. The concentrations in the 9.7 × 10-11-7.8 × 10-10 M region used in this work corresponded to the expected number of 0.4-3.4 molecules, and the calibration curve in this region showed good linearity. Taking into account the enhancement factor of solvent, the molar absorption coefficient of solute, and the optimization of the optical arrangement, the present result, which was the determination limit of 0.34, was consistent with that previously reported. The relation between molecular behavior in the probing volume and the signal was discussed. The average temperature rise in the probing volume by the photothermal effect for the single OEP molecule was estimated as 3.1 μK, and this value was detectable, based on conventional thermal lens measurements for bulk scale sample.

Original languageEnglish
Pages (from-to)2112-2116
Number of pages5
JournalAnalytical Chemistry
Volume73
Issue number9
DOIs
Publication statusPublished - 2001 May 1
Externally publishedYes

ASJC Scopus subject areas

  • Analytical Chemistry

Fingerprint Dive into the research topics of 'Determination of subyoctomole amounts of nonfluorescent molecules using a thermal lens microscope: Subsingle-molecule determination'. Together they form a unique fingerprint.

  • Cite this