Mid-Infrared Spectroscopy of the Interstellar Medium

莱西博士建造了一台阶梯光栅摄谱仪 比其他现有仪器更敏感， 中红外中高分辨率光谱学 波长 有了这笔赠款，他将继续他的开创性工作， 在光谱的这个波长区域。 三个项目将 强调：1）他将研究气体的相对重要性- 相反应和颗粒表面反应对分子组成的影响 通过观察气体中各种分子的吸收， 和固相; 2）他将研究纯旋转线 氢分子的发射，以了解 冲击气体和光解区域，并确定 氢与一氧化碳的比例;和3）他将观察 氖和硫离子的中红外发射线，以研究 红外发光星系的运动学和激发。 中红外光谱有两个主要优点 天文光谱学区域：小星际 相对于较短波长的消光， 存在几个有趣的光谱特征，特别是 分子的振动跃迁和精细结构线 离子。 许多物体由于灭绝而无法观测， 在可见光或近红外波长下， 中红外线 分子和离子的光谱线提供了 关于运动学和物理条件的宝贵信息 最新发现的天体 莱西博士的光谱仪显示 仪器质量的显著进步， 探索中红外波段的物体。

Dr. Lacy has constructed an echelle spectrograph which is an order of magnitude more sensitive than other available instruments for spectroscopy of moderate to high resolution at mid-infrared wavelengths. With this grant he will continue his pioneering work in this wavelength region of the spectrum. Three projects will be emphasized: 1) He will investigate the relative importance of gas- phase and grain-surface reactions on the composition of molecular clouds by observing absorption of various molecules in the gaseous and solid phases; 2) He will study the pure rotational line emission of molecular hydrogen, to learn about the conditions in shocked gas and photodissociation regions, and to determine the ratio of hydrogen to carbon monoxide; and 3) He will observe the mid-infrared emission lines of ions of neon and sulfur to study the kinematics and excitation of infrared luminous galaxies. There are two principal advantages to the mid-infrared spectral region for astronomical spectroscopy: the small interstellar extinction relative to that at shorter wavelengths, and the presence of several interesting spectral features, notably vibrational transitions of molecules and fine-structure lines of ions. Many objects which are unobservable, because of extinction, at visible or near-infrared wavelengths become accessible in the mid-infrared. Spectral lines of molecules and ions provide valuable information about the kinematics and physical conditions of the newly revealed objects. Dr. Lacy's spectrograph represents a significant advance in the quality of instrumentation for exploring objects at mid-infrared wavelengths.