Nonlinear Optical Responses from Au Surfaces as a Function of Temperature and Atmospheric Composition
Nonlinear Optical Responses from Au Surfaces as a Function of Temperature and Atmospheric Composition
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Au 表面的非线性光学响应与温度和大气成分的函数关系
DOI：
10.1021/acs.jpcc.2c04065
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Walker, Robert A.
中科院分区：
文献类型：
--
作者：
McNally, Marshall T.;Walker, Robert A.
二次谐波产生（SHG）被用来测量金的二阶非线性光学响应作为温度的函数和作为环境大气成分的函数。使用定制的温度控制组件，在19 ° C和260 °C之间，在含有不同量（0-100%）O2和余量N2的气氛下，从Au表面测量SHG信号。SHG强度随温度的升高而减小，这一结果被解释为在较高温度下电子-声子散射增加。令人惊讶的是，SHG强度也取决于环境气氛，在空气（20%O2）中测量的SHG信号比室温下在N2中测量的信号大102倍。这种SHG强度对大气成分的依赖性在高温下消失。系统地将O2滴定到N2进料中表明，在室温下，来自Au的SHG信号在15%O2下饱和。尽管广泛接受O2不吸附到散装Au表面，我们建议，这些结果是一致的弱物理吸附的表面过量的O2在Au-气体界面。拟合此O2增强Au的SHG响应的Langmuir等温线意味着吸附能的顺序为0.1 eV，与先前报道的DFT计算结果一致。CO以类似于O2的方式影响来自Au的SHG信号，这意味着SHG增强是由于Au的导带电子背键到O2或CO吸附物上的空轨道。
Second harmonic generation (SHG) was used to measure gold’s second-order nonlinear optical response as a function of temperature and as a function of ambient atmosphere composition. Using a bespoke temperature-controlled assembly, SHG signal was measured from an Au surface between 19 and 260 °C under atmospheres containing varying amounts (0–100%) of O2with a balance of N2. SHG intensity diminished with increasing temperature, a result that is interpreted in terms of increased electron–phonon scattering at higher temperatures. Surprisingly, SHG intensity also depended on ambient atmosphere, with the SHG signal measured in air (20% O2) being ∼2 times larger than that measured in N2at room temperature. This dependence of SHG intensity on atmospheric composition disappeared at high temperatures. Systematically titrating O2into an N2feed showed that the room-temperature enhancement of SHG signal from Au saturated at ∼15% O2. Despite widespread acceptance that O2does not adsorb to a bulk Au surface, we propose that these results are consistent with a weakly physisorbed surface excess of O2at the Au–gas interface. Fitting this O2enhancement of Au’s SHG response to a Langmuir isotherm implies an adsorption energy on the order of 0.1 eV, consistent with results from previously reported DFT calculations. CO affects the SHG signal from Au in a manner similar to that of O2, implying that the SHG enhancement is due to back-bonding of Au’s conduction band electrons into vacant orbitals on either the O2or CO adsorbates.
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影响因子：
4.4
作者：
Gibson, K. D.;Sibener, S. J.;Troya, Diego
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DOI：
10.1063/1.5066451
发表时间：
2019
期刊：
The Journal of chemical physics
影响因子：
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影响因子：
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作者：
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