Fourier-transform infrared spectroscopy and proton-transfer-reaction–mass spectrometry are used in a complementary way to study gas-phase processes during decomposition of ethanol in a microwave plasma torch. Decomposition products (C, C₂ and simple hydrocarbons) reassemble into higher hydrocarbons and graphene nuclei and further grow into graphene nanosheets (GNS). Depending on microwave power, ethanol flow rate and molecular gas admixture, the material structure changes from amorphous to crystalline. The presence of C_2n + 1H _y species was found to be responsible for the formation of defects in the GNS structure. O₂ and H₂ admixtures change the gas temperature axial profile and consequently modify reaction pathways influencing growth and production rate of GNS. Determination of reaction pathway selectivity enables us to predict whether high-quality or defective GNS are produced.

中文翻译：

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石墨烯纳米片微波等离子体气相合成反应途径的转变：从非晶结构到高度结晶结构

傅里叶变换红外光谱和质子转移反应-质谱以互补的方式用于研究微波等离子体炬中乙醇分解过程中的气相过程。分解产物（C、C ₂和简单的碳氢化合物）重新组装成高级碳氢化合物和石墨烯核，并进一步生长成石墨烯纳米片 (GNS)。根据微波功率、乙醇流速和分子气体混合物，材料结构从无定形变为结晶。发现C _{2 n  + 1} H _y物质的存在是造成GNS 结构中缺陷形成的原因。O ₂和 H ₂ 外加剂改变了气体温度的轴向分布，从而改变了影响 GNS 生长和生产速率的反应途径。确定反应途径选择性使我们能够预测是否产生了高质量或有缺陷的 GNS。