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Title: Ultrasensitive Photothermal Spectroscopy: Harnessing the Seebeck Effect for Attogram-Level Detection
Molecular-level spectroscopy is crucial for sensing and imaging applications, yet detecting and quantifying minuscule quantities of chemicals remains a challenge, especially when they surface-adsorb in low numbers. Here, we introduce a photothermal spectroscopic technique that enables the sensing and quantification of adsorbates with an attogram detection limit. Our approach utilizes the Seebeck effect in a microfabricated nanoscale thermocouple junction, incorporated into the apex of a microcantilever. We observe minimal thermal mass exhibited by the sensor which maintains exceptional thermal insulation. The temperature variation driving the thermoelectric junction arises from the non-radiative decay of molecular adsorbates' vibrational states on the tip. We demonstrate the detection of physisorbed trinitrotoluene (TNT) and dimethyl methylphosphonate (DMMP) molecules, as well as representative polymers, with an estimated mass sensitivity of 10-18 g and a temperature resolution of 40 mK.  more » « less
Award ID(s):
2029375
NSF-PAR ID:
10447277
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
Nano Letters
ISSN:
1530-6984
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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