title: Probing organic ligands and their binding schemes on nanocrystals by mass spectrometric and FT-IR spectroscopic imaging.
abstract: We report an analysis method to identify conjugated ligands and their binding states on semiconductor nanocrystals based on their molecular information. Surface science techniques, such as time-of-flight secondary-ion mass spectrometry (ToF-SIMS) and FT-IR spectroscopy, are adopted based on the micro-aggregated sampling method. Typical trioctylphosphine oxide-based synthesis methods of CdSe/ZnS quantum dots (QDs) have been criticized because of the peculiar effects of impurities on the synthesis processes. Because the ToF-SIMS technique provides molecular composition evidence on the existence of certain ligands, we were able to clearly identify n-octylphosphonic acid (OPA) as a surface ligand on CdSe/ZnS QDs. Furthermore, the complementary use of the ToF-SIMS technique with the FT-IR technique could reveal the OPA ligands' binding state as bidentate complexes.
authors: Department of Chemistry and KI for the NanoCentury, KAIST, Daejeon 34141, Korea. sangwoohan@kaist.ac.kr and Center for Nano-Bio Measurement, Korea Research Institute of Standard and Science, Daejeon 34113, Korea. tglee@kriss.re.kr.
authors: Jin Gyeong
authors: JG
authors: Son
authors: Program in Nano Science and Technology, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 08826, Korea and Advanced Institute of Convergence Technology, Suwon 16227, Korea.
authors: Eunjin
authors: E
authors: Choi
authors: Program in Nano Science and Technology, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 08826, Korea and Advanced Institute of Convergence Technology, Suwon 16227, Korea.
authors: Yuanzhe
authors: Y
authors: Piao
authors: Department of Chemistry and KI for the NanoCentury, KAIST, Daejeon 34141, Korea. sangwoohan@kaist.ac.kr.
authors: Sang Woo
authors: SW
authors: Han
authors: Center for Nano-Bio Measurement, Korea Research Institute of Standard and Science, Daejeon 34113, Korea. tglee@kriss.re.kr.
authors: Tae Geol
authors: TG
authors: Lee