This work was supported in part by the Washington Space Grant Consortium under Award NNX10AK64H.

1.规划实验<ol><li>进行文献的调查，以评估之前完成的工作使用感兴趣的激光介质，这对于这个实验是CH 2 F 2。确定所有已知的激光辐射以及有关该行的所有信息，如波长和频率。可用13,31称为激光辐射的几个调查- 37。 </li><li>编译作为重点放在事先傅立叶激光介质的分子的所有光谱研究改造34和光声研究38,39。 </li></ol> 2.生成远红外激光辐射<ol><li>安全概述。 <ol><li>制定与CO 2和远红外激光系统工作时，包括适当护眼实验室标准作业程序。 </li></ol></li><li>校准和标定。 <ol><li>校准每个CO2 升使用ASER基于光栅的频谱分析仪，根据生产商的方案设计的二氧化碳激光器。 </li><li>对准末端反射镜和使用He-Ne激光，使得它们的辐射被聚焦在MIM二极管检测器耦合镜中的远红外线激光腔。 </li><li>直接从CO 2激光器泵入远红外激光腔通过一个氯化钠窗口辐射以约72○具有相对于所述腔轴线的角度。 </li><li>直接来自两个CO 2的参考激光器要么它们各自的低压力荧光基准单元或共线到使用波束分离器和附加反射镜的MIM二极管检测器的辐射。 </li></ol></li><li>检测远红外激光辐射。 <ol><li>使用标准的金属波兰语镍基每隔数天。 </li><li>压接一个25微米的钨丝成铜柱和弯曲线到configur通货膨胀如图 3所示。 </li><li>调整导线的长度，因此，它是被测量的辐射的10至20个波长之间。 </li><li>电化学通过施加电压（大约3.5至5伏）到该溶液中蚀刻该金属丝在饱和氢氧化钠（NaOH）溶液的尖端。 </li><li>再蚀刻具有低电压（小于1伏）的前端。这个变粗糙的电线的前端，并提高二极管的性能。 </li><li>冲洗导线用蒸馏水。 </li><li>将铜后进入MIM二极管的住房，一旦线是干的。 </li><li>放置电线与使用一个精细螺旋输送机和级系统的镍基极接触。触点产生跨越100至500Ω的二极管的电阻检测和测量的远红外激光辐射时通常使用。 </li></ol></li><li>代远红外激光辐射。 <ol><li>将CO 2泵浦激光器在一个特定的激光EM传输停滞， 例如 ，9 第36页 。 </li><li>旋转上的 CO 2泵激光器的千分表来回来实现对波束停止最大强度。 </li><li>调节CO 2的泵浦激光器的光栅的倾斜来实现对波束停止最大强度。 </li><li>重复步骤2.4.2和2.4.3，直到输出功率为CO 2泵浦激光器优化出现在梁停止。 </li><li>从CO 2泵浦激光的路径中删除束停止。 </li><li>打开并对准光断续进入的 CO 2泵激光器的光束路径。 </li><li>打开的CH 2 F 2气缸阀引入的远红外线激光介质进入远红外激光腔。 </li><li>调整的入口管线的计量阀，直到大约10帕达到的压力。 注意：只有近似压力是必要的，因为它被用作系统扫描所述远红外激光c进行方式avity。 </li><li>设置输出耦合器的位置，使得其最外端部是从激光腔的作为对激光谐振腔的外部指示的校准尺度的中间大约1厘米。 注意：只有近似位置是必要的，因为它被用作系统扫描的远红外线激光腔中的方法。 </li><li>通过旋转校准千分表来回调整可移动的远红外激光反射镜的约0.25毫米增量的位置。同时调通过其增益曲线的CO 2的泵浦激光器通过改变跨越CO 2的泵激光器的压电换能器（PZT）施加的电压的频率。 </li><li>如果没有信号在示波器显示器上观察到，重复步骤准则草案2.4.10与输出耦合器移动到其下一个位置，其中所述尖端是约1.5厘米，从激光谐振腔，作为对激光的外侧由在刻度盘的中间腔。 </li><li>如果没有信号在示波器显示器上观察到，重复步骤准则草案2.4.10与输出耦合器移动到其下一个位置，其中所述尖端是约2厘米的激光腔的作为对激光的外侧由在刻度盘的中间腔。 </li><li>如果没有信号在示波器显示器上观察到，重复步骤2.4.9至2.4.12具有大约19 Pa的远红外激光器压力与在入口线的计量阀调节。 </li><li>如果没有信号在示波器显示器上观察到，重复步骤2.4.9至2.4.12具有大约27 Pa的远红外激光器压力与在入口线的计量阀调节。 </li><li>如果没有信号在示波器显示器上观察到的，将波束停止入的 CO 2的泵浦激光器的路径和关闭阀门的CH 2 F 2气缸直到远红外激光器压力是约0帕。 </li><li>设置的 CO 2泵使用步骤2.4.2至2.4.4激光到下一个激光发射，例如，9个P 34，优化输出功率。 </li><li>重复步骤2.4.5至2.4.16直到通过CO 2泵激光器产生的所有排放被使用。当搜索远红外激光线，把重点放在CO 2泵浦激光器发射的频率与在步骤1.2确定任何吸收区域重叠。 </li></ol></li><li>表征远红外激光辐射。 <ol><li>同时调节远红外线激光介质的压力，施加到CO 2泵激光器的PZT的电压，而输出耦合器的位置，直到远红外线激光发射器的输出功率被最大化（由最大峰到确定从MIM二极管检测器的峰值信号作为观察示波器显示，类似上图4）。 </li><li>转动千分表顺时针直到远红外线激光发射上观察到示波器显示。记录千分表的位置。 </li><li>转动千分表顺时针为对应于相同的远红外线激光发射一个额外的20个模态。记录千分表的位置。 </li><li>减去步骤2.5.2和2.5.3的千分表的位置。除以10这种差异，得到远红外激光器发射的波长。 </li><li>重复步骤2.5.2至2.5.4一个总共五次并平均远红外线激光发射的波长。通过遍历至少20相邻的纵向模式测定平均激光波长为±0.5μm的1-Σ不确定性。 </li><li>测量的远红外激光辐射的极化，相对于CO 2的泵浦辐射，使用一个金线栅偏振器（394线/ cm）或一个布鲁斯特偏振器。 </li></ol></li></ol> 3.确定远红外激光频率<ol><li>认荷兰国际集团的CO 2激光参考排放。 <ol><li>计算是根据它测得的波长的远红外线激光发射的频率。 </li><li>识别组的 CO 2激光参考线，其频率差在几GHz计算出的频率为远红外线激光发射40。用于这种测量的一种典型的列表显示在表1中。 </li></ol></li><li>搜索外差拍信号。 <ol><li>识别所述第一组的 CO 2激光参考线，并设置在它们各自的激光发射每条CO 2基准激光。 </li><li>使用步骤2.4.2至2.4.4和显示器电源电表优化输出功率每个CO 2激光参考。 <ol><li>调整光圈，无论是内部或外部的各个基准激光，使得如通过在所示的监视器功率计测量从每个CO 2的参照用激光的功率大约为100毫瓦图2。 </li></ol></li><li>阻止使用波束停止，同时疏通从CO 2激光器参考辐射的CO 2泵浦激光器的辐射。 </li><li>打开并对准光断续进入的 CO 2激光器参考的共线光束路径。 </li><li>优化最大峰-峰电压上使用多个反射镜，分束器的MIM二极管检测器的每个的 CO 2参考激光发射，和2.54厘米焦距的ZnSe平凸透镜，同时观察示波器上的输出， 与图5类似。 </li><li>阻止使用波束停止，同时疏通从CO 2泵浦激光辐射的CO 2激光器参考辐射。 </li><li>重新优化的 CO 2泵激光器和远红外线激光，根据需要，从而使远红外线激光发射具有与观察到在示波器上的最大峰-峰电压。 </li><li>断开吨他MIM二极管检测器输出的示波器，并将其连接到放大器的输出频谱分析仪观察。 </li><li>不阻止从CO 2激光器参考辐射。 </li><li>卸下光盘菜刀调节二氧化碳泵和参考激光器。 </li><li>设置频谱分析仪上的40 MHz的范围内，并通过使用频谱分析仪的调节旋钮手动扫描这个频率范围内搜索的拍音信号在1.5GHz的增量。 </li><li>如果没有拍频信号被观测到，来自放大器断开MIM二极管的输出，并把它连接到示波器。 </li><li>方框从CO 2激光器参考辐射并重新插入光断续进入的 CO 2激光器泵的路径。 </li><li>重复步骤3.2.2至必要3.2.13直到频谱分析仪已被用于搜索0和12千兆赫之间的差拍信号。 </li><li>如果没有拍频信号被观测到，REPE在步骤3.2.2至3.2.14与另一组的CO 2的参考激光线直到该差拍信号被观察到或CO 2的参照用激光线的所有可能的组是耗尽。 </li></ol></li><li>稳定的CO 2的参考频率。 <ol><li>介于0和900V，施加电压到第一CO 2的参照用激光的PZT，使得从各自的荧光基准单元的信号是在中心处的羔羊浸， 在图6中示出并在观察示波器，如图7。 </li><li>激活使用定制的锁定/伺服放大器，以便它保持锁定到兰姆凹陷的中心施加到第一CO 2的参照用激光的PZT反馈电压。 </li><li>重复步骤3.3.1和3.3.2的第二CO 2激光参考。 </li><li>直观地监视前置放大器的示波器上的输出，如在图7中，连接到确定基准激光器保持锁定状态。 </li></ol></li><li>测量拍频。 <ol><li>居中的频谱分析仪显示器上的拍频信号，并调整其振幅最大化显示其大小。 </li><li>将频谱分析仪，以查看节拍信号的两个同时的痕迹， 如在图8中，通过选择清除写入特征为迹线1和线2的一个跟踪将显示瞬时信号，而另一个将记录的最大信号（使用在频谱分析仪第二一丝最大保持功能）。 </li><li>上旋转的远红外激光腔中的千分表来回增益曲线对于给定的腔模式。 </li><li>使用频谱分析仪上的视图功能得到对称的图案，一旦冻结第二（最大保持）跟踪。 </li><li>略微转动千分表顺时针降低远红外激光腔的长度。同时观察潜艇equent小移在频谱分析仪上拍频由于在远红外激光的频率这种轻微增加。 </li><li>发生在全宽标志的对称模式（最大保持迹​​线）的使用与频谱分析仪三角洲特征标记功能，半高点。 </li><li>测量使用的频谱分析仪的跨度对特征拍频信号的中心频率。 </li><li>重复步骤3.4.1至3.4.7。 </li><li>在脱离/伺服驱动器锁每个CO 2激光引用从它的中心频率解锁每个激光器，重新优化每个CO 2激光参考。 </li><li>使用步骤3.3.1至3.3.4重新锁定参考激光器。 </li><li>为总共6次测量重复步骤3.4.1至10年3月4日。一旦完成，解开其中心频率每个CO 2激光参考。 </li><li>使用这些节拍FRE计算的远红外线激光发射的订正频率quencies获得精确的预测的第二组的 CO 2参考激光线。 </li><li>识别一组不同的CO 2的参考激光线，其频率差在计算出的频率为远红外激光器发射的几GHz。 </li><li>优化的下一组上的MIM二极管检测器的 CO 2激光器的参考线，并使用步骤3.2.2通过在必要3.2.15获得拍频信号。 </li><li>使用步骤3.3.1至3.3.4锁定一套新的二氧化碳参考激光线。 </li><li>为总共6次测量重复步骤3.4.1至10年3月4日。一旦完成，解开其中心频率每个CO 2激光参考。 </li><li>插入光束停止进入的 CO 2泵和参考激光器的路径。 </li></ol></li><li>计算的远红外线激光的频率。 <ol><li>计算未知远红外激光频率，ν 区，使用所测量的是在通过关系频 FIR = |νCO 2（Ⅰ）-νCO 2（II）的 | ±|ν 拍 |式。 1 其中|νCO 2（Ⅰ）-νCO 2（II）的 |是差频由两个CO 2激光器的参考和综合的幅度|ν 拍 |是拍频的幅度。该±符号公式。 1，从步骤3.4.5实验确定。 </li><li>获得的平均频率，并计算不确定。 </li></ol></li></ol>

Certain commercial equipment is identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the authors, nor does it imply that the equipment identified is necessarily the best available for the purpose.

有迹象表明，需要一些额外的讨论中的协议中的几个关键步骤。当测量的远红外激光波长，如在步骤2.5.3概述的，它保证了远红外激光器发射的正在使用相同的模式是重要的。 （即TEM 00，TEM 01，等）可在激光腔中产生一个远红外激光波长的多种模式，从而以识别所使用的适当的相邻的腔模以测量波长13,29是很重要的， 41。以协助消除高阶模式，虹膜包括在每...

首先由HÖCKER执行的远红外激光频率的测量和同事在1967年他们测量的频率用于从直接放电氰化氢激光的311和337微米的排放量与微波信号的高次谐波将它们混合在硅二极管1。为了测量更高的频率，链激光器和谐波混频装置用于产生激光谐波2。最终2稳定化的二氧化碳（CO 2）激光器被选择，以合成所需的差频率3,4。今天，远红外线激光频率可达4太赫兹可以使用由两个产生的差频的只有第一谐波这种技术来测量稳定化的 CO 2参考激光器。更高频率的激光辐射也可以使用二次谐波测定，如由甲醇同位素异冠心病2 9 ​​赫兹激光排放OH和CH 3 </sUB&gt; 18 OH 5,6多年来，激光频率的精确测量已经影响了一些科学实验7,8和允许通过的电表由度量衡在巴黎大会一个新的定义， 1983年9 - 11 外差技术，如所描述的那些，已经在由光泵分子激光器产生的远红外激光频率测量也是很有好处的。由于光泵分子激光器由Chang和桥12的发现，千光泵远红外激光排放已产生与多种激光媒体。例如，二氟甲烷（CH 2 F 2）和其同位素产生超过250激光辐射时光学地由CO 2激光器泵浦。它们的波长范围是从大约95.6至1714.1微米13 - </s达&gt; 15近75％，这些激光排放有其频率测量，而一些已光谱分配16 - 18。 这些激光器，和它们的精确测量的频率，已经于高分辨率光谱的进步起到了至关重要的作用。它们提供的激光气体的红外光谱研究的重要信息。通常，这些激光频率被用来验证红外和远红外光谱的分析，因为它们提供的激发振动状态的水平，往往从吸 ​​收光谱19直接难以接近之间的连接。它们也可以作为初级辐射来源的研究调查过性，短命的自由基与激光磁共振技术20。有了这个极其敏感的技术，在顺磁性原子，分子转动和振转塞曼光谱和分子离子可以是Recorded而且随着调查用来创建这些自由基的反应率的能力进行分析。 在这项工作中，一个光泵浦分子激光， 如图 1所示，已被用来产生从二氟甲烷远红外激光辐射。这个系统包括一个连续波（CW） 的 CO 2激光器的泵和一个远红外激光腔。的反射镜内部的远红外激光腔重定向的 CO 2激光辐射向下抛光铜管，在经过26反射终止于所述腔的端部，散射任何剩余泵辐射之前。因此，远红外激光介质是使用横向泵送几何激发。产生激光的动作，若干变量被调节，同时一些，和所有随后的优化一次激光辐射是观察。 在该实验中，远红外激光辐射由金属INSU监视荡器 - 金属（MIM）点接触型二极管检测器。自1969年以来21所述的MIM二极管检测器已用于激光频率测量- 23在激光频率的测量，所述MIM二极管检测器之间的两个或更多个辐射源入射到二极管谐波混频器。所述MIM二极管探测器由一个削尖的钨丝接触经过光学研磨的镍基24。镍基体具有天然存在的薄氧化物层，其在绝缘层。 27以下最初在文献中记载的方法-一次激光发射检测，它的波长，偏振，强度和优化的操作压力，而其频率使用三激光外差技术25测定的记录。 4. 图2显示了光泵浦激光分子与具有独立的频率站两个附加连续波CO 2激光器参考bilization系统，利用在4.3微米的荧光信号的兰姆凹陷来自外部，低压参考单元28。这个手稿概述用于搜索远红外激光排放以及推定方法其波长和准确地确定它们的频率的过程。关于三激光外差技术细节以及各种部件和系统的运行参数可以在补充表A中一起引用4，25-27，29和30。

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Vacuum pump</td>
			<td>Leybold</td>
			<td>Trivac D4A</td>
			<td>HE-175 oil; Quantity = 3</td>
		</tr>
		<tr>
			<td>Vacuum pump</td>
			<td>Leybold</td>
			<td>Trivac D8B or D16B</td>
			<td>Fomblin Fluid; Quantity = 1 of each</td>
		</tr>
		<tr>
			<td>Vacuum pump</td>
			<td>Leybold</td>
			<td>Trivac D25B</td>
			<td>HE-175 oil; Quantity = 1</td>
		</tr>
		<tr>
			<td>Optical chopper with controller</td>
			<td>Stanford Research Systems</td>
			<td>SR540</td>
			<td></td>
		</tr>
		<tr>
			<td>Lock-in amplifier</td>
			<td>Stanford Research Systems</td>
			<td>SR830</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectrum analyzer</td>
			<td>Agilent</td>
			<td>E4407B</td>
			<td>ESA-E Series, 9 kHz to 26.5 GHz Spectrum Analyzer</td>
		</tr>
		<tr>
			<td>Amplifier&#160;</td>
			<td>Miteq</td>
			<td>AFS-44</td>
			<td>Provides amplification of signals between 2 and 18 GHz. The amplifier is powered by a Hewlett Packard triple output DC power supply, model E3630A.</td>
		</tr>
		<tr>
			<td>Amplifier&#160;</td>
			<td>Avantek</td>
			<td>AWL-1200B</td>
			<td>Provides amplification of signals less than 1.2 GHz.</td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Hewlett Packard</td>
			<td>E3630A</td>
			<td>Low voltage DC power supply for amplifier.</td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Glassman</td>
			<td>KL Series</td>
			<td>High voltage power supply for the CO2 lasers; Quantity = 2; negative polarity</td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Fluke</td>
			<td>412B</td>
			<td>High voltage power supply used with the NIST Asymmetric HV Amp</td>
		</tr>
		<tr>
			<td>Detector</td>
			<td>Judson Infrared Inc</td>
			<td>J10D</td>
			<td>For fluorescence cell; Quantity = 2</td>
		</tr>
		<tr>
			<td>CO2 laser spectrum analyzer</td>
			<td>Optical Engineering&#160;</td>
			<td>16-A</td>
			<td>Currently sold by Macken Instruments Inc.</td>
		</tr>
		<tr>
			<td>Thermal imaging plates with UV light</td>
			<td>Optical Engineering&#160;</td>
			<td></td>
			<td>Primarily used for aligning the CO2 reference lasers. Currently sold by Macken Instruments Inc.</td>
		</tr>
		<tr>
			<td>Resistors</td>
			<td>Ohmite&#160;</td>
			<td>L225J100K</td>
			<td>100 kW, 225 W. Between 4 to 6 resistors are used in each ballast system. Each CO2 laser has its own ballast system. Fans are used to cool the resistors.</td>
		</tr>
		<tr>
			<td>HV relay, SPDT</td>
			<td>CII Technologies</td>
			<td>H-17</td>
			<td>Quantity = 3; one for each CO2 laser</td>
		</tr>
		<tr>
			<td>Amplifier&#160;</td>
			<td>Princeton Applied Research</td>
			<td>PAR 113</td>
			<td>Used with fluorescence cell; Quantity = 2</td>
		</tr>
		<tr>
			<td>Oscilloscope</td>
			<td>Tektronix</td>
			<td>2235A</td>
			<td>Similar models are also used; Quantity = 2</td>
		</tr>
		<tr>
			<td>Oscilloscope/Differential amplifier</td>
			<td>Tektronix</td>
			<td>7903 oscilloscope with 7A22 differential amplifier</td>
			<td></td>
		</tr>
		<tr>
			<td>Power meter with sensor</td>
			<td>Coherent</td>
			<td>200</td>
			<td>For use below 10 W.&#160; This is the power meter shown in Figure 2.</td>
		</tr>
		<tr>
			<td>Power meter with sensor</td>
			<td>Scientech, Inc</td>
			<td>Vector S310</td>
			<td>For use below 30 W</td>
		</tr>
		<tr>
			<td>Multimeter</td>
			<td>Fluke</td>
			<td>73III</td>
			<td>Similar models are also used; Quantity = 3</td>
		</tr>
		<tr>
			<td>Data acquisition</td>
			<td>National Instruments</td>
			<td>NI cDAQ 9174 chassis with NI 9223 input module</td>
			<td>Uses LabVIEW software</td>
		</tr>
		<tr>
			<td>Simichrome polish</td>
			<td>Happich GmbH</td>
			<td></td>
			<td>Polish for the Nickel base used in the MIM diode detector. Although the Nickel base can be used immediately after polishing, a 12 hour lead time is typically recommended.</td>
		</tr>
		<tr>
			<td>Pressure gauge</td>
			<td>Wallace and Tiernan</td>
			<td>61C-1D-0050</td>
			<td>Series 300; for CO2 laser; Quantity = 3</td>
		</tr>
		<tr>
			<td>Pressure gauge with controller</td>
			<td>Granville Phillips</td>
			<td>Series 375</td>
			<td>For far-infrared laser</td>
		</tr>
		<tr>
			<td>Zirconium Oxide felt</td>
			<td>Zircar Zirconia</td>
			<td>ZYF felt</td>
			<td>Used as a beam stop</td>
		</tr>
		<tr>
			<td>Zirconium Oxide board</td>
			<td>Zircar Zirconia</td>
			<td>ZYZ-3 board</td>
			<td>Used as a beam stop; Quantity = 4</td>
		</tr>
		<tr>
			<td>Teflon sheet</td>
			<td>Scientific Commodities, Inc</td>
			<td>BB96312-1248</td>
			<td>1/32 inch thick; used for the far-infrared laser output window</td>
		</tr>
		<tr>
			<td>Polypropylene</td>
			<td>C-Line sheet protectors</td>
			<td>61003</td>
			<td>used for the far-infrared laser output window</td>
		</tr>
		<tr>
			<td>Vacuum grease</td>
			<td>Apiezon</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Kepco</td>
			<td>NTC 2000</td>
			<td>PZT power supply</td>
		</tr>
		<tr>
			<td>PZT tube</td>
			<td>Morgan Advanced Materials</td>
			<td></td>
			<td>1 inch length, 1 inch outer diameter, 0.062 inch thickness, reverse polarity (positive voltage on outside); Quantity = 3</td>
		</tr>
		<tr>
			<td>ZnSe (AR coated)</td>
			<td>II-VI Inc</td>
			<td></td>
			<td>CO2 laser window (Quantity = 3), lens, and beam splitter (Quantity 3)</td>
		</tr>
		<tr>
			<td>NaCl window</td>
			<td>Edmond Optics</td>
			<td></td>
			<td>Quantity = 1</td>
		</tr>
		<tr>
			<td>CaF window</td>
			<td>Edmond Optics</td>
			<td></td>
			<td>Quantity = 2</td>
		</tr>
		<tr>
			<td>Laser mirrors and gratings</td>
			<td>Hyperfine, Inc</td>
			<td></td>
			<td>Gold-coated; includes positioning mirrors</td>
		</tr>
		<tr>
			<td>Glass laser tubes and reference cells</td>
			<td>Allen Scientific Glass</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MIM diode detector</td>
			<td>Custom Microwave, Inc</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Other</td>
			<td></td>
			<td></td>
			<td>Other materials include magnetic bases, base plates, base clamps, XYZ translation stage, etc.</td>
		</tr>
	</tbody>
</table>

characterizing far-infrared laser emissions and the measurement of their frequencies

的产生和远红外线辐射的随后的测量发现在高分辨率光谱，射电天文学，和太赫兹成像众多应用。约45年，连贯，远红外辐射的产生使用光泵分子激光器已经完成。一旦远红外激光辐射被检测到，这些激光辐射的频率被用三激光外差技术测量。利用这种技术，该未知频率从光泵浦分子激光器是具有两个稳定的，红外线参考频率之间的差频混合。由独立的二氧化碳激光器生成这些基准频率，每个稳定来自外部，低压参考细胞使用荧光信号。的已知和未知的激光频率之间所产生的跳动是由一个金属 - 绝缘体 - 金属点接触二极管检测器，其输出上的规格观察监视特鲁姆分析仪。这些激光排放之间的拍频随后测量并结合已知的参考频率来推断未知远红外激光频率。与此技术测量的产生的一种-Σ分数不确定性对激光频率是在10 7±5份。准确确定远红外激光器发射的频率是非常关键的，因为它们经常被用来作为对其他测量值的参考，如在高采用激光磁共振自由基 - 分辨率光谱调查。作为该调查，二氟甲烷，CH 2 F 2的一部分，用作远红外线的激光介质。在所有八远红外激光的频率进行测定，第一次用频率范围从0.359至1.273的THz。这三个激光排放此调查期间被发现和报告与他们的最佳操作压力，偏振相对于CO 2的</suB&gt;泵浦激光器和力量。

如所提到的，报告了远红外激光器发射的频率是一个平均的至少12次测量与至少两个不同组的CO 2的参考激光线进行的。 表2概述当使用所记录的为235.5微米激光发射的数据9 P 04 CO 2泵浦激光器。对于这种远红外线激光发射，拍频的14个人测量记录。在使用9 R 10和 9个P 38 的 CO 2基准激光的排放量记录在第一组测量。对于步骤3.4.5，作为远红外线?...

Watch this Scientific Journal Video about Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies at JoVE.com

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

We describe the generation of far-infrared radiation using an optically pumped molecular laser along with the measurement of their frequencies with heterodyne techniques. The experimental system and techniques are demonstrated using difluoromethane (CH2F2) as the laser medium whose results include three new laser emissions and eight measured laser frequencies.

表征远红外激光辐射及其频率的测量

The generation and subsequent measurement of far-infrared radiation has found numerous applications in high-resolution spectroscopy, radio astronomy, and ...

characterizing-far-infrared-laser-emissions-measurement-their

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SCIENTISTS IN ACTION

11.9K 次观看.  Central Washington University. We describe the generation of far-infrared radiation using an optically pumped molecular laser along with the measurement of their frequencies with heterodyne techniques. The experimental system and techniques are demonstrated using difluoromethane (CH2F2) as the laser medium whose results include three new laser emissions and eight measured laser frequencies.

视频: Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

Spatial Separation of Molecular Conformers and Clusters

Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold molecular beams. However, these beams often contain multiple conformers and clusters, even at low rotational temperatures. We present an experimental methodology that allows the spatial separation of these constituent parts of a molecular beam expansion. Using an electric deflector the beam is separated by its mass-to-dipole moment ratio, analogous to a bender or an electric sector mass spectrometer spatially dispersing charged molecules on the basis of their mass-to-charge ratio. This deflector exploits the Stark effect in an inhomogeneous electric field and allows the separation of individual species of polar neutral molecules and clusters. It furthermore allows the selection of the coldest part of a molecular beam, as low-energy rotational quantum states generally experience the largest deflection. Different structural isomers (conformers) of a species can be separated due to the different arrangement of functional groups, which leads to distinct dipole moments. These are exploited by the electrostatic deflector for the production of a conformationally pure sample from a molecular beam. Similarly, specific cluster stoichiometries can be selected, as the mass and dipole moment of a given cluster depends on the degree of solvation around the parent molecule. This allows experiments on specific cluster sizes and structures, enabling the systematic study of solvation of neutral molecules.

We present a technique that allows the spatial separation of different conformers or clusters present in a molecular beam. An electrostatic deflector is used to separate species by their mass-to-dipole moment ratio, leading to the production of gas-phase ensembles of a single conformer or cluster stoichiometry.

分子构象器和星团的空间分离

Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold ...

科研

工程学

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement is used. Here we operate a Nd:YAG laser at a frequency of 10 Hz at the fundamental wavelength of 1,064 nm. The 14 nsec pulses with anenergy of 190 mJ/pulse are focused to a 50 &#181;m spot size to generate a plasma from optical breakdown or laser ablation in air. The microplasma is imaged onto the entrance slit of a 0.6 m spectrometer, and spectra are recorded using an 1,800 grooves/mm grating an intensified linear diode array and optical multichannel analyzer (OMA) or an ICCD. Of interest are Stark-broadened atomic lines of the hydrogen Balmer series to infer electron density. We also elaborate on temperature measurements from diatomic emission spectra of aluminum monoxide (AlO), carbon (C2), cyanogen (CN), and titanium monoxide (TiO).
The experimental procedures include wavelength and sensitivity calibrations. Analysis of the recorded molecular spectra is accomplished by the fitting of data with tabulated line strengths. Furthermore, Monte-Carlo type simulations are performed to estimate the error margins. Time-resolved measurements are essential for the transient plasma commonly encountered in LIBS.

Measurement and Analysis of Atomic Hydrogen and Diatomic Molecular AlO, C2, CN, and TiO Spectra Following Laser-induced Optical Breakdown

Time-resolved atomic and diatomic molecular species are measured using LIBS. The spectra are collected at various time delays following the generation of optical breakdown plasma with Nd:YAG laser radiation&#160;and are analyzed to infer electron density and temperature.

测量和原子氢和双原子分子ALO，C分析<sub&gt; 2</sub&gt;，CN和二氧化钛光谱承接激光诱导光学击穿

In this work, we present time-resolved measurements of atomic and diatomic spectra following laser-induced optical breakdown. A typical LIBS arrangement ...

Design and Use of a Full Flow Sampling System (FFS) for the Quantification of Methane Emissions

The use of natural gas continues to grow with increased discovery and production of unconventional shale resources. At the same time, the natural gas industry faces continued scrutiny for methane emissions from across the supply chain, due to methane&#39;s relatively high global warming potential (25-84x that of carbon dioxide, according to the Energy Information Administration). Currently, a variety of techniques of varied uncertainties exists to measure or estimate methane emissions from components or facilities. Currently, only one commercial system is available for quantification of component level emissions and recent reports have highlighted its weaknesses.
In order to improve accuracy and increase measurement flexibility, we have designed, developed, and implemented a novel full flow sampling system (FFS) for quantification of methane emissions and greenhouse gases based on transportation emissions measurement principles. The FFS is a modular system that consists of an explosive-proof blower(s), mass airflow sensor(s) (MAF), thermocouple, sample probe, constant volume sampling pump, laser based greenhouse gas sensor, data acquisition device, and analysis software. Dependent upon the blower and hose configuration employed, the current FFS is able to achieve a flow rate ranging from 40 to 1,500 standard cubic feet per minute (SCFM). Utilization of laser-based sensors mitigates interference from higher hydrocarbons (C2+). Co-measurement of water vapor allows for humidity correction. The system is portable, with multiple configurations for a variety of applications ranging from being carried by a person to being mounted in a hand drawn cart, on-road vehicle bed, or from the bed of utility terrain vehicles (UTVs). The FFS is able to quantify methane emission rates with a relative uncertainty of &#177; 4.4%. The FFS has proven, real world operation for the quantification of methane emissions occurring in conventional and remote facilities.

Design and Use of a Full Flow Sampling System FFS for the Quantification of Methane Emissions

We have designed, developed, and implemented a novel full flow sampling system (FFS) for quantification of methane emissions and greenhouse gases from across the natural gas supply chain.

设计和全流采样系统（FFS）的使用甲烷排放的量化

The use of natural gas continues to grow with increased discovery and production of unconventional shale resources. At the same time, the natural gas ...

Optical Trap Loading of Dielectric Microparticles In Air

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly scattered dielectric microparticles adhered to a glass substrate are momentarily detached using ultrasonic vibrations generated by a piezoelectric transducer (PZT). Then, the optical beam focused on a selected particle lifts it up to the optical trap while the vibrationally excited microparticles fall back to the substrate. A particle may be trapped at the nominal focus of the trapping beam or at a position above the focus (referred to here as the levitation position) where gravity provides the restoring force. After the measurement, the trapped particle can be placed at a desired position on the substrate in a controlled manner. 
In this protocol, an experimental procedure for selective optical trap loading in air is outlined. First, the experimental setup is briefly introduced. Second, the design and fabrication of a PZT holder and a sample enclosure are illustrated in detail. The optical trap loading of a selected microparticle is then demonstrated with step-by-step instructions including sample preparation, launching into the trap, and use of electrostatic force to excite particle motion in the trap and measure charge. Finally, we present recorded particle trajectories of Brownian and ballistic motions of a trapped microparticle in air. These trajectories can be used to measure stiffness or to verify optical alignment through time domain and frequency domain analysis. Selective trap loading enables optical tweezers to track a particle and its changes over repeated trap loadings in a reversible manner, thereby enabling studies of particle-surface interaction.

A protocol for launching and stably trapping selected dielectric microparticles in air is presented.

介电微粒的光阱装载在空气中

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly ...

Generation of Size-controlled Poly (ethylene Glycol) Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

Uniform and size-controllable poly (ethylene glycol) diacrylate (PEGDA) droplets could be produced via the flow focusing process in a microfluidic device. This paper proposes a semi-three-dimensional (semi-3D) flow-focusing microfluidic chip for droplet formation. The polydimethylsiloxane (PDMS) chip was fabricated using the multi-layer soft lithography method. Hexadecane containing surfactant was used as the continuous phase, and PEGDA with the ultraviolet (UV) photo-initiator was the dispersed phase. Surfactants allowed the local surface tension to drop and formed a more cusped tip which promoted breaking into tiny micro-droplets. As the pressure of dispersed phase was constant, the size of droplets became smaller with increasing continuous phase pressure before dispersed phase flow was broken off. As a result, droplets with size variation from 1 &#181;m to 80 &#181;m in diameter could be selectively achieved by changing the pressure ratio in two inlet channels, and the average coefficient of variation was estimated to be below 7%. Furthermore, droplets could turn into micro-beads by UV exposure for photo-polymerization. Conjugating biomolecules on such micro-beads surface have many potential applications in the fields of biology and chemistry.

Generation of Size-controlled Poly ethylene Glycol Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

Here, we present a protocol to illustrate the fabrication processes and verifying experiments of a semi-three-dimensional (semi-3D) flow-focusing microfluidic chip for droplet formation.

Semi-3-Dimensional 流聚焦微流控装置产生尺寸控制的聚乙二醇二丙烯酸酯液滴

Uniform and size-controllable poly (ethylene glycol) diacrylate (PEGDA) droplets could be produced via the flow focusing process in a microfluidic device. ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

纤维素纸非接触式共振腔电谱研究的方法研究

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...

Measuring Sub-23 Nanometer Real Driving Particle Number Emissions Using the Portable DownToTen Sampling System

The current particle size threshold of the European Particle Number (PN) emission standards is 23 nm. This threshold could change because future combustion engine vehicle technology may emit large amounts of sub-23 nm particles. The Horizon 2020 funded project DownToTen (DTT) developed a sampling and measurement method to characterize particle emissions in this currently unregulated size range. A PN measurement system was developed based on an extensive review of the literature and laboratory experiments testing a variety of PN measurement and sampling approaches. The measurement system developed is characterized by high particle penetration and versatility, which enables the assessment of primary particles, delayed primary particles, and secondary aerosols, starting from a few nanometers in diameter. This paper provides instruction on how to install and operate this Portable Emission Measurement System (PEMS) for Real Drive Emissions (RDE) measurements and assess particle number emissions below the current legislative limit of 23 nm.

Presented here is the DownToTen (DTT) portable emission measurement system to assess real driving automotive emissions of sub-23 nm particles.

使用便携式 DownToTen 采样系统测量低于 23 纳米实际驱动粒子数排放

The current particle size threshold of the European Particle Number (PN) emission standards is 23 nm. This threshold could change because future ...

3D Printing - Evaluating Particle Emissions of a 3D Printing Pen

Three-dimensional (3D) printing as a type of additive manufacturing shows continuing increase in application and consumer popularity. The fused filament fabrication (FFF) is an inexpensive method used most frequently by consumers. Studies with 3D printers have shown that during the printing process particulate and volatile substances are released. Handheld 3D printing pens also use the FFF method but the consumer&#8217;s proximity to the 3D pens gives reason to higher exposure compared to a 3D printer. At the same time, 3D printing pens are often marketed for children who could be more sensitive to the printing emission. The aim of this study was to implement a low cost method to analyze the emissions of 3D printing pens. Polylactide (PLA) and acrylonitrile butadiene styrene (ABS) filaments of different colors were tested. In addition, filaments containing metal and carbon nanotubes (CNTs) were analyzed. An 18.5 L chamber and sampling close to the emission source was used to characterize emissions and concentrations near the breathing zone of the user.
Particle emissions and particle size distributions were measured and the potential release of metal particles and CNTs investigated. Particle number concentrations were found in a range of 105 - 106 particles/cm3, which is comparable to previous reports from 3D printers. Transmission electron microscopy (TEM) analysis showed nanoparticles of the different thermoplastic materials as well as of metal particles and CNTs. High contents of metal were observed by inductively coupled plasma mass spectrometry (ICP-MS).
These results call for a cautious use of 3D pens due to potential risk to the consumers.

This protocol presents a method to analyze the emission of 3D printing pens. Particle concentration and particle size distribution of the released particle is measured. Released particles are further analyzed with transmission electron microscopy (TEM). Metal content in filaments is quantified by inductively coupled plasma mass spectrometry (ICP-MS).

3D 打印 - 评估 3D 打印笔的粒子排放

Three-dimensional (3D) printing as a type of additive manufacturing shows continuing increase in application and consumer popularity. The fused filament ...

Solution Blow Spinning of Polymeric Nano-Composite Fibers for Personal Protective Equipment

Light-weight, protective armor systems typically consist of high modulus (&#62;109 MPa) and high-strength polymeric fibers held in place with an elastic resin material (binder) to form a non-woven, unidirectional laminate. While significant efforts have focused on improving the mechanical properties of the high-strength fibers, little work has been undertaken to improve the properties of the binder materials. To improve the performance of these elastomeric polymer binders, a relatively new and simple fabrication process, known as solution blow spinning, was used. This technique is capable of producing sheets or webs of fibers with average diameters ranging from the nanoscale to the microscale. To achieve this, a solution blow spinning (SBS) apparatus has been designed and built in the laboratory to fabricate non-woven fiber mats from polymer elastomer solutions.
In this study, a commonly used binder material, a styrene-butadiene-styrene block-co-polymer dissolved in tetrahydrofuran, was used to produce nanocomposite fiber mats by adding metallic nanoparticles (NPs), such as iron oxide NPs, that were encapsulated with silicon oil and thus incorporated in the fibers formed via the SBS process. The protocol described in this work will discuss the effects of the various critical parameters involved in the SBS process, including the polymer molar mass, the selection of the thermodynamically appropriate solvent, the polymer concentration in solution, and the carrier gas pressure to assist others in performing similar experiments, as well as provide guidance to optimize the configuration of the experimental setup. The structural integrity and morphology of the resultant non-woven fiber mats were examined using scanning electron microscopy (SEM) and elemental X-ray analysis via energy-dispersive X-ray spectroscopy (EDS). The goal of this study is to evaluate the effects of the various experimental parameters and material selections to optimize the structure and morphology of the SBS fiber mats.

The primary goal of this study is to describe a protocol to prepare polymeric fiber mats with consistent morphology via solution blow spinning (SBS). We aim to use SBS to develop novel, tunable, flexible polymeric fiber nanocomposites for various applications, including protective materials, by incorporating nanoparticles in a polymer-elastomer matrix.

用于个人防护装备的聚合物纳米复合纤维的溶液吹丝

Light-weight, protective armor systems typically consist of high modulus (&#62;109 MPa) and high-strength polymeric fibers held in place with an elastic ...

Fabrication of a Fabry-P&amp;#233;rot Etalon for Application in Trace-Gas Spectroscopy

Fabrication of a Low-Cost, Fiber-Coupled, and Air-Spaced Fabry-P&#233;rot Etalon

Fabry-P&#233;rot etalons (FPE) have found their way into many applications. In fields such as spectroscopy, telecommunications, and astronomy, FPEs are used for their high sensitivity as well as their exceptional filtering capability. However, air-spaced etalons with high finesse are usually built by specialized facilities. Their production requires a clean room, special glass handling, and coating machinery, meaning commercially available FPEs are sold for a high price. In this article, a new and cost-effective method to fabricate fiber-coupled FPEs with standard photonic laboratory equipment is presented. The protocol should serve as a step-by-step guide for the construction and characterization of these FPEs. We hope this&#160;will enable researchers to conduct fast and cost-effective prototyping of FPEs for various fields of application. The FPE, as presented here, is used for spectroscopic applications. As shown in the representative results section via proof of principle measurements of water vapor in ambient air, this FPE has a finesse of 15, which is sufficient for the photothermal detection of trace concentrations of gases.

Author Spotlight: Fabrication of a Low-Cost, Fiber-Coupled, and Air-Spaced Fabry-P&amp;#233;rot Etalon  

This protocol describes the construction of a low-cost, discrete, fiber-coupled, and air-spaced Fabry-Perot etalon with various applications, such as in trace-gas spectroscopy. The fabrication is possible in any facility with standard optical laboratory equipment available.

制造低成本、光纤耦合和空气间隔的法布里-佩罗标准具

Fabry-P&#233;rot etalons (FPE) have found their way into many applications. In fields such as spectroscopy, telecommunications, and astronomy, FPEs are ...