Determination of Heterogeneous Photochemistry Related to Atmospheric Reactive Nitrogen Species

氮氧化物(NOx=NO NO2)在地面臭氧形成、平流层臭氧消耗和酸沉积中起着关键作用。了解大气中活性氮物种的化学组成(NOY，其中NOY定义为NOx和NOx的大气氧化产物的总和)对于污染预防和控制工作至关重要。虽然大量NOY的均相气相光化学已被研究，但对硝酸(HNO3)和过硝酸(HO2NO2)等NOY物种的多相光化学却知之甚少。在低NOx环境中，吸附在地面上的HNO3的光解被认为是HONO的主要白天来源。尤其是对共沉积在表面的HNO3/H2O的紫外吸收截面和光解量子产率知之甚少。该项目致力于表征表面吸附的硝酸在无水蒸气和存在水蒸气的情况下的非均相光解，表面共沉积的硝酸/水，以及表面吸附的HO2NO2。用布鲁斯特角腔衰荡光谱测定了表面吸附的HNO_3、HNO_3/H_2O和H_2NO_2的紫外吸收截面随波长的变化。通过将激光光解与布鲁斯特角腔衰荡光谱(熔融二氧化硅表面)或腔衰荡光谱(铝或冰膜表面)相结合来测量这些物种的异相光解的光解路径和产物产量。该项目将为评估非均相光解在将氮氧化物储存库转化为活性形式和产生对流层奇数氢自由基方面的作用提供必要的信息。该项目将直接导致对研究生和博士后学者的研究培训。除了项目主任、博士后学者和研究生在国内外会议上发表研究成果，并在专业期刊上发表成果外，项目主任朱磊博士还计划定期在当地高校授课，与该地区的科学家分享研究成果，激发学生对科学的兴趣，促进不同机构之间的智力交流。首席调查员(PI)还计划加强外联工作，促进大学教育多样化和包容性的目标。纽约州立大学奥尔巴尼分校有现有的外展计划，如牧羊人计划。牧羊人项目的目标是与历史上少数族裔大学的教职员工建立长期合作伙伴关系。PI计划成为纽约州立大学奥尔巴尼分校牧羊人计划的活跃成员。

Nitrogen oxides (NOx = NO+NO2) play a pivotal role in ground-level ozone formation, stratospheric ozone depletion, and acid deposition. Understanding atmospheric chemistry of reactive nitrogen species (NOY, where NOY is defined as the sum of NOx and the atmospheric oxidation products of NOx) is critical to pollution prevention and control efforts. While the homogeneous gas phase photochemistry of a large number of NOY has been studied, much less is known about the heterogeneous photochemistry of NOY species such as nitric acid (HNO3) and peroxynitric acid (HO2NO2). The photolysis of adsorbed HNO3 on ground surfaces has been proposed as a major daytime source of HONO in low-NOx environments. Little is known in particular about the UV absorption cross sections and the photolysis quantum yields of HNO3/H2O co-deposited on surface. The project seeks to characterize heterogeneous photolysis of surface-adsorbed HNO3 both in the absence and in the presence of water vapor, of HNO3/H2O co-deposited on surface, and of surface-adsorbed HO2NO2. Wavelength-dependent UV absorption cross sections of surface-adsorbed HNO3, HNO3/H2O, and HO2NO2 will be determined using Brewster-angle cavity ring-down spectroscopy. The photodissociation pathways and product yields from the heterogeneous photolysis of these species will be measured by combining laser photolysis either with Brewster angle cavity ring-down spectroscopy (fused silica surface) or with cavity ring-down spectroscopy (Al or ice film surface). The project will provide information essential to the assessment of the role of heterogeneous photolysis in converting NOx reservoirs into active forms and in producing tropospheric odd hydrogen radicals.The project will directly lead to the research training of a graduate student and a postdoctoral scholar. In addition to presenting research findings at national and international conferences by the project director, postdoctoral scholar and graduate student, and publishing results in professional journals, the project director, Dr. Lei Zhu, plans to periodically give lectures in the local colleges and universities in the region to share the research results with scientists in the area, excite students' interests in science, and promote intellectual exchanges between different institutions. The Principal Investigator (PI) also plants to increase outreach efforts and to contribute to the goal of diversity and inclusiveness in university education. SUNY-Albany has existing outreach programs such as the Shepherd Project. The Shepherd Project has the goal of establishing long-term partnerships with faculty at historically minority colleges. The PI plans to become an active member in the Shepherd Program at SUNY-Albany.