TELD sampling brings multimodal analytical chemistry to the nanoscale

About This Grant

With the support of the Chemical Measurement and Imaging Program in the Division of Chemistry, Professors De Vries and Gordon at the University of California, Santa Barbara, will develop a novel technique to combine high resolution imaging with detailed chemical analysis. This work addresses a difficult challenge and a critical need in many scientific areas that require the analysis of miniscule samples, especially for complex organic compounds. Examples of applications include chemical diagnostics, analysis of artifacts and art, archeology, geology, soft materials, polymer physics, catalysis, materials science, microelectronics, and biological samples. The technique, which is akin to a ‘nanoscale-biopsy’, will use a two-step approach whereby material is first collected from a nanoscale size area of the sample and then analyzed by sophisticated chemical techniques. The project will involve collaborations with colleagues in diverse fields, such as biology programs at UCSB – to study genetic material in tissue, the Getty Conservation Institute – to study paint layers in classical paintings, and Materials Science programs – to study heterogeneous junctions in solar cells. Both undergraduate and graduate students will receive training in the design and construction of advanced experimental instrumentation, complex computer simulation, and conducting fundamental research. The instrumentation to be developed will employ a modified atomic force microscope (AFM) for both imaging and material collection. The latter will be achieved by tip-enhanced laser desorption (TELD), in which the field of a laser pulse is focused by the AFM tip, acting as a plasmonic antenna to locally collect femtogram levels of intact molecules from a surface for subsequent chemical analysis. The analysis will be performed by resonance enhanced multiphoton ionization, matrix-assisted laser desorption/ionization mass spectrometry, and PCR amplification and sequencing for biological samples. Given these capabilities, the microscope will provide detailed physicochemical and optical information about materials at the level of their intrinsic heterogeneity; as such, significant contributions to fundamental and applied science in many fields can be envisioned. The work will also provide fundamental data related to exciting and manipulating evanescent optical fields with plasmonic structures, and detailed information about the materials and thermal chemistry of laser desorption processes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.