动态力显微镜中能量耗散的温度依赖性
Temperature dependence of the energy dissipation in dynamic force microscopy
摘要：
动态力显微镜中的能量耗散通常用粘附滞后机制来描述。随着温度的升高，这种机制的效率会降低。为了验证这一预测，我们已经测量了地形和耗散数据与动态力显微镜的温度范围从100 K到300 K。我们使用在KBr（001）上生长的3，4，9，10-二萘嵌苯四甲酸二酐（PTCDA），这两种材料在大的频移下表现出强的耗散信号。在室温下，能量耗散到样品（或尖端）是1.9 eV/周期PTCDA和2.7 eV/周期KBr，分别，是在良好的协议与粘附滞后机制。PTCDA表面的能量耗散随着温度的升高而降低，产生负温度系数。对于溴化钾基板，我们发现相反的行为：随着温度的升高，耗散能量的增加。虽然PTCDA的情况下的负温度系数同意相当好的粘附滞后模型，发现KBr的正斜率指向一个迄今为止未知的耗散机制。
英文摘要：
The dissipation of energy in dynamic force microscopy is usually described in terms of an adhesion hysteresis mechanism. This mechanism should become less efficient with increasing temperature. To verify this prediction we have measured topography and dissipation data with dynamic force microscopy in the temperature range from 100 K up to 300 K. We used 3,4,9,10-perylenetetracarboxylic-dianhydride (PTCDA) grown on KBr(001), both materials exhibiting a strong dissipation signal at large frequency shifts. At room temperature, the energy dissipated into the sample (or tip) is 1.9 eV/cycle for PTCDA and 2.7 eV/cycle for KBr, respectively, and is in good agreement with an adhesion hysteresis mechanism. The energy dissipation over the PTCDA surface decreases with increasing temperature yielding a negative temperature coefficient. For the KBr substrate, we find the opposite behaviour: an increase of dissipated energy with increasing temperature. While the negative temperature coefficient in case of PTCDA agrees rather well with the adhesion hysteresis model, the positive slope found for KBr points to a hitherto unknown dissipation mechanism.
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