Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 11: New Instruments and Methods

CPP 11.12: Talk

Tuesday, March 27, 2012, 12:45–13:00, C 243

Bimetallic cantilever microcalorimetry with high energy and time resolution — •Florian M. Spirkl, Richard Schröter, Friedrich Esch, and Uli Heiz — TU München, Lehrstuhl f. Physikalische Chemie

Temperature induced bending of bimetallic cantilevers has been established in recent years as sensor for microcalorimetry, offering high energy resolution [1]. The position of the cantilever tip is read out using a laser and a position sensitive optical device (PSD). We present a differential read out setup that improves the time resolution from typical 100 ms [2] down to 1 ms, the response time of the cantilevers that is time-limiting.

The experimental setup consists of a reactive sample and an inert reference cantilever that are read out differentially using a high frequency deflection mirror. Both bend simultaneously due to environment changes, whereas the investigated process develops heat only on the sample cantilever. For calibration, both sample and reference cantilever can be heated by two laser diodes. This cantilever setup works under UHV conditions, and in reactive gas as well as in liquid environment. The sensitivity of the ambient cantilever setup can be estimated to be 150 nJ with 1 ms time resolution.

First experiments within a temperature controlled liquid flow cell will be presented, including measurements on thiol-gold bonding upon formation of self-assembled monolayers (SAM).

[1] J.R. Barnes et. al., Review of Scientific Instruments 65, 3793, (1994) [2] H.P. Lang et. al., Materials Today 8, 30 (2005)