Rovibrational transitions and nuclear spin conversion of methane in parahydrogen crystals
Rovibrational transitions and nuclear spin conversion of methane in parahydrogen crystals
复制标题
仲氢晶体中甲烷的旋转振动跃迁和核自旋转换
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
T. Momose
中科院分区：
文献类型：
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作者：
Masaaki Miki;T. Momose
固体仲氢由于其高的光谱分辨率，是一种优良的基体分离光谱学基体。在这里，我们描述的振转结构和核自旋转换嵌入仲氢晶体的红外吸收光谱研究。在4.8K时，CH 4的振动-转动共振峰的强度随时间变化。这些变化被解释为伴随着J=1→J=0转动弛豫的I=1→I=2核自旋转换的结果。上J=1旋转状态的半衰期是不变的，除了高达2%的orthohydrogen分子，但减少与超过10% orthohydrogen分子。在更高的正氢浓度下的衰变速率的增加表明，由于正氢分子混合了核自旋态，这加速了转换，因此穿过CH 4的磁场梯度。
Solid parahydrogen is an excellent matrix for matrix-isolation spectroscopy because of its high spectral resolution. Here we describe the rovibrational structure and nuclear spin conversion of CH4 embedded in parahydrogen crystals studied by infrared absorption spectroscopy. The vibration–rotation absorptions of CH4 exhibit time-dependent intensity changes at 4.8 K. These changes are interpreted to be a result of the I=1→I=2 nuclear spin conversion that accompanies the J=1→J=0 rotational relaxation. The half-lifetime of the upper J=1 rotational state is unchanged by the addition of up to 2% orthohydrogen molecules but decreases with more than 10% orthohydrogen molecules. The increase of the decay rate at higher orthohydrogen concentration indicates that the magnetic field gradient across CH4 due to the orthohydrogen molecules mixes the nuclear spin states, which accelerates the conversion.