Posted: June 15, 2009

Asylum Research Introduces Ztherm Modulated Thermal Analysis with Sub-Zeptoliter Resolution

(Nanowerk News) Asylum Research, a technology leader in Scanning Probe and Atomic Force Microscopy (SPM/AFM) has announced the new Ztherm Modulated Local Thermal Analysis Option for its MFP-3D™ and Cypher™ AFMs. Ztherm provides highly localized heating with sensitivity to <=10-22 liter (sub-zeptoliter) materials property changes, more than an order of magnitude improvement in volume over that previously available with commercial systems.
A standing problem with existing AFM-based thermal analysis systems is thermally induced bending of the cantilever that results in spurious deflection signals and variable loads being applied during heating. Asylum has developed a patent-pending cantilever compensation and control solution that corrects this problem, providing constant-load detection of thermally induced melting (Tm), phase transitions (Tg) and other morphological and compliance effects for materials studies and material identification – for areas less than 20nm x 20nm.
Sub-zeptoliter thermal decomposition of Insulin Fibers
Sub-zeptoliter thermal decomposition of Insulin Fibers. (a) shows a 1x2?m AC (tapping) mode image of insulin fibers deposited on a mica surface. After imaging, a series of thermal-bending compensated, lowtemperature thermal cycles were performed in a 12x6 array of points. A small selection of those locations are indicated by the colored markers in both (a) and (b). (b) shows an AC image of the same region after the thermal cycling was complete, showing numerous gaps in the fibers where thermomechanical decomposition has occurred. (c) shows the local thermal expansion (top deflection plots) and resonant frequency shifts (bottom plots) associated with the thermal cycles, color coded by location. Note the clear signal associated with thermal decomposition of the fibers visible in the resonant frequency shift curves. The deflection curves show no significant response at the same temperature. Note that some tip broadening has occurred during the thermal cycling that reduces the resolution between (a) and (b). Because the heating cycles were made at constant load, compensated for the thermally induced bending of the lever, the resonant shifts can be primarily attributed to thermal decomposition, rather than simple mechanical effects.
In addition to standard thermal analysis capabilities, the Ztherm package can also be used to evaluate contact stiffness and dissipation as a function of temperature with advanced techniques such Dual AC Resonance Tracking (DART). The contact stiffness and dissipation – measured at the cantilever resonance – are much more sensitive to temperature dependent properties, including surface melting and transition temperatures, than conventional deflection-based measurements. In addition, integrated piezo actuation allows high resolution AC imaging of samples for surface topographical mapping before and after thermal measurements. The Ztherm option is compatible with and includes Anasys ThermaleverTM probes.
Dr. Roger Proksch, Asylum Research President commented, “Our new Ztherm option is the most powerful thermal analysis package on the market today, with sensitivity, resolution and capabilities beyond anything else available. With the ability to be used in combination with our new DART technique, we believe Ztherm will enhance existing research avenues and open up new directions for analysis of thermal effects and material identification on scales previously impossible.”
Source: Asylum Research (press release)
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