Negligible Sample Heating from Synchrotron Infrared Beam
Negligible Sample Heating from Synchrotron Infrared Beam
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同步加速器红外光束对样品的加热可忽略不计
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
W. McKinney
中科院分区：
文献类型：
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作者：
Michael C. Martin;N. Tsvetkova;J. Crowe;W. McKinney
同步辐射光源用于红外（IR）光谱显微镜提供了大大增加的亮度，使得能够在衍射受限的空间分辨率下进行高质量的IR测量。这种能力允许基于同步加速器的红外光谱显微镜被应用于生物应用的空间分辨率上的一个单一的哺乳动物细胞的大小的顺序。问题随之而来，“强烈的同步加速器光束会伤害生物样品吗？”中红外光子的能量太低，无法直接破坏键;然而，它们可能会因加热而对生物分子造成损害。在这项工作中，我们提出的测量，显示可以忽略不计的样品加热效应从衍射限制同步辐射红外光源。所使用的样品是完全水合的脂质双层组成的二棕榈酰磷脂酰胆碱（DPPC），它经历了相变从凝胶到液晶态在加热过程中约315 K。当样品通过相变时，几个IR活性振动模式的频率明显偏移。我们校准，然后使用这些移动的振动模式作为原位温度传感器。
The use of synchrotron sources for infrared (IR) spectromicroscopy provides greatly increased brightness that enables high-quality IR measurements at diffraction-limited spatial resolutions. This capability permits synchrotron-based IR spectromicroscopy to be applied to biological applications at spatial resolutions on the order of the size of a single mammalian cell. The question then arises, “Does the intense synchrotron beam harm biological samples?” Mid-IR photons are too low in energy to break bonds directly; however, they could cause damage to biological molecules due to heating. In this work, we present measurements that show negligible sample heating effects from a diffraction-limited synchrotron IR source. The sample used is fully hydrated lipid bilayers composed of dipalmitoylphosphatidylcholine (DPPC), which undergoes a phase transition from a gel into a liquid-crystalline state at about 315 K during heating. Several IR-active vibrational modes clearly shift in frequency when the sample passes through the phase transition. We calibrate and then use these shifting vibrational modes as an in situ temperature sensor.