Formation of radical species in photolyzed CH₄:N₂ ices     

Robert Hodyss  Heather R. Howard  Jay D. Goguen 《Icarus》2011,214(2):748-753

We report photochemical studies of thin cryogenic ice films composed of N₂, CH₄ and CO in ratios analogous to those on the surfaces of Neptune’s largest satellite, Triton, and on Pluto. Experiments were performed using a hydrogen discharge lamp, which provides an intense source of ultraviolet light to simulate the sunlight-induced photochemistry on these icy bodies. Characterization via infrared spectroscopy showed that C₂H₆ and C₂H₂, and HCO are formed by the dissociation of CH₄ into H, CH₂ and CH₃ and the subsequent reaction of these radicals within the ice. Other radical species, such as C₂, , CN, and CNN, are observed in the visible and ultraviolet regions of the spectrum. These species imply a rich chemistry based on formation of radicals from methane and their subsequent reaction with the N₂ matrix. We discuss the implications of the formation of these radicals for the chemical evolution of Triton and Pluto. Ultimately, this work suggests that , CN, HCO, and CNN may be found in significant quantities on the surfaces of Triton and Pluto and that new observations of these objects in the appropriate wavelength regions are warranted.  相似文献   

H₂O₂ production by high-energy electrons on icy satellites as a function of surface temperature and electron flux     

Kevin P. Hand  Robert W. Carlson 《Icarus》2011,215(1):226-233

Chemistry on the icy surface of Europa is heavily influenced by the incident energetic particle flux from the jovian magnetosphere. The majority (>75%) of this energy is in the form of high energy electrons (extending to >10 MeV). We have simulated the electron irradiation environment of Europa with a vacuum system containing a high-energy electron gun for irradiation of ice samples formed on a gold mirror cooled with a cryostat. Pure water films of ∼2.6 μm thickness were grown at 100 K and then either cooled (to 80 K), warmed (to 120 K) or left at 100 K and subsequently irradiated with 10 keV electrons. The production of hydrogen peroxide (H₂O₂) was monitored by observation of the 2850 cm⁻¹ (3.5 μm) band. Equilibrium concentrations of H₂O₂, in units of percent by number H₂O₂ relative to water, were found to be 0.043% (80 K), 0.029% (100 K), and 0.0063% (120 K). These values are 33%, 22%, and 5%, respectively, that of the reported surface concentration on the leading hemisphere of Europa (Carlson, R.W., Anderson, M.S., Johnson, R.E., Smythe, W.D., Hendrix, A.R., Barth, C.A., et al. [1999]. Science 283(5410), 2062-2064) and less than the equilibrium concentrations formed by ion irradiation. In addition to the ice film temperature, the current of electrons was varied between different experiments to determine the production and destruction of H₂O₂ as a function of both electron flux and ice temperature. Variation in current was found to have little effect on the results other than accelerating arrival at radiolytic equilibrium.  相似文献   

Comparing gravity and gravity gradient surveys     

Gary J. Barnes  John M. Lumley  Phill I. Houghton  Richard J. Gleave 《Geophysical Prospecting》2011,59(1):176-187

Noise levels in marine and airborne full tensor gravity gradiometer surveys together with conventional land, marine and airborne gravity surveys are estimated and analysed in gridded form, resulting in relations that detail how these different survey systems can be compared analytically. After defining survey parameters including line spacing, speed and instrument bandwidth, the relations estimate the noise levels that result on either grids of gravity (gz) or gravity gradient (Gzz) as a function of the spatial filtering often applied during geological interpretation. Such comparisons are believed to be a useful preliminary guide for survey selection and planning.  相似文献   

常见绿松石品种特征及充填处理的鉴定     

罗跃平  邓旺晖  段体玉  王春生 《岩石矿物学杂志》2011,30(Z1):181-186

总结了我国市场上大量常见的不同产地的天然绿松石的特征,同时对比我国市场常见的充填处理绿松石的特征,研究了天然与充填处理绿松石的一般鉴别特征,发现处理绿松石的颜色深浅、颜色分布、包裹体、外观与天然绿松石均有较大的区别。还利用红外光谱对天然的和充填处理的绿松石进行了测试,发现充填处理绿松石在1 735、1 600、1 500 cm^-1附近可见吸收峰,表明绿松石内部充填了人工类树脂,可作为鉴定充填处理绿松石的有力证据。  相似文献   

水汽吸收和下垫面发射率对晴空大气红外窗区遥感影响的综合分析     

巴桑  许丽生  刘海磊  丁继烈  邓小波  刘志红 《地理与地理信息科学》2011,27(2):41-45

从数学上探讨了晴空大气红外窗区通道遥感陆面特性水汽吸收和陆面发射率的综合影响。首先,基于辐射传输方程推导出大气水汽含量和陆面发射率(ε)引起红外窗区通道遥感陆面亮温(Tg)变化的数学表达式,指出红外辐射在传输过程中水汽吸收衰减的影响主要是引起大气透过率的变化;分析了在高温高湿和低温干燥等不同地区,红外窗区通道的大气透过率所受到的不同程度的衰减,以及水汽吸收衰减和陆面发射率对不同的红外窗区通道的影响。此外,还建立了一个红外窗区通道遥感陆面温度与地面亮温差ΔT=(Ts-Tg,imax)与水汽含量变化Δq和陆面发射率ε的二元多项式拟合方程,进一步分析大气水汽含量和陆面发射率对不同的红外窗区通道遥感的影响;指出红外短波窗区通道不但受太阳辐射污染严重,而且受陆面发射率变化的影响激烈,特别是在寒冷干燥的亚北极冬季。最后强调,为了精确地反演陆面温度,最好采用热红外窗区通道;必须考虑大气订正,特别是在高温高湿区;同时应该考虑陆面发射率等因子的作用。  相似文献   

FT-IR measurements of cold C₃H₈ cross sections at 7–15 μm for Titan atmosphere     

Keeyoon Sung  Geoffrey C. Toon  Arlan W. Mantz  Mary Ann H. Smith 《Icarus》2013

We present absorption cross sections of propane (C₃H₈) at temperatures from 145 K to 297 K in the 690–1550 cm⁻¹ region. Pure and N₂-broadened spectra were measured at pressures from 3 Torr to 742 Torr using a Bruker IFS125 FT-IR spectrometer at JPL. The gas absorption cell, developed at Connecticut College, was cooled by a closed-cycle helium refrigerator. The cross sections were measured and compiled for individual spectra recorded at various experimental conditions covering the planetary atmosphere and Titan. In addition to the cross sections, a propane pseudoline list with a frequency grid of 0.005 cm⁻¹, was fitted to the 34 laboratory spectra. Line intensities and lower state energies were retrieved for each line, assuming a constant width. Validation tests showed that the pseudoline list reproduces discrete absorption features and continuum, the latter contributed by numerous weak and hot band features, in most of the observed spectra within 3%. Based on the pseudoline list, the total intensity in the 690–1550 cm⁻¹ region was determined to be 52.93 (±3%) × 10⁻¹⁹ cm⁻¹/(molecule cm⁻²) at 296 K; this value is within 3% of the average from four earlier studies. Finally, the merit of the pseudoline approach is addressed for heavy polyatomic molecules in support of spectroscopic observation of atmospheres of Titan and other planets. The cold cross sections will be submitted to the HITRAN database (hitran.harvard.edu), and the list of C₃H₈ pseudolines will be available from a MK-IV website of JPL (http://mark4sun.jpl.nasa.gov/data/spec/Pseudo).  相似文献   

华南及邻近海域夏季深对流活动气候特征   总被引：8，自引：0，他引：8  

郑永光  陈炯 《热带气象学报》2011,27(4):495-508

利用具有较高时空分辨率与很好时空完整性的11年(1996—2007年，无2004年)6—8月静止卫星数字红外云图和TBB资料，给出了华南及邻近海域夏季深对流活动气候分布特征，并同文献中给出的雷暴日分布和闪电分布进行了对比分析。结果表明，华南及邻近海域夏季深对流活动有5个活跃中心，其月变化特征与大尺度环流背景密切相关。6月华南陆地区域深对流活动较活跃，7、8月南海海域深对流活动较活跃。华南及邻近海域深对流活动具有间歇性发展特征，其周期大约为3～5候，但华南海岸线附近为海陆过渡区域，深对流活动持续比较活跃且间歇性特征不突出；深对流活动旬与候变化特征表明华南陆地区域和南海海域深对流活动呈现反相关变化趋势。深对流活动的日变化特征显示该区域陆地与海洋、山地与盆地的热力差异所导致的海陆风环流与山谷风环流使得华南海岸线附近区域的深对流活动具有午后向陆地传播、午夜后向海洋传播的特征，山地与盆地的深对流活动具有显著的午夜后向盆地传播的特征。深对流活动日变化特征还表明该区域不仅具有一般热对流、海洋深对流和双峰型深对流等多种类型对流活动，且两广海岸线邻近区域具有持续时间长、日变化较不显著的海岸线深对流和其它天气系统触发和维持的深对流。  相似文献   

关于OH/IR星的质量损失率计算公式的讨论     

熊关柱  陈培生 《天文学报》2000,41(2):181-191

利用几种不同的半经验公式计算一批OH／IR星的质量损失率,并通过比较计算结果来讨论所用的公式．在一些情况下,计算质量损失率必须先给定气尘比．通过计算出样品星的气尘比,并讨论气尘比的变化情况,以修正由尘埃质量损失率到总质量损失率的关系式．  相似文献   

海洋微藻多糖微波提取法研究   总被引：1，自引：0，他引：1  

刘四光  李文权  邓永智 《海洋通报》2007,26(4):105-110

选取自养小球藻(Chlorella autotrophica)为实验材料,采用微波法提取多糖,以温度、时间、pH以及微波功率4个因子建立正交实验,考察单因素影响情况。实验结果表明,在温度70℃、时间30min、pH为7、功率为600W条件下粗多糖的产率最高,为291.13mg/g(粗多糖/干重),远高于传统热水浸提法所得粗多糖产率(78.52mg/g,粗多糖/干重),且所得粗多糖与热水浸提法获得的粗多糖具有相似的红外光谱。说明,在一定的实验条件下,与热水浸提法相比,微波提取法不仅不会破坏多糖的结构,还有耗时短、有较高的多糖产率的优势。  相似文献   

活动色球双星HR1099近红外分光光度观测     

翟迪生  张效愚  王俊杰 《中国天文和天体物理学报》1995,(2)

本文发表了强活动色球双星ＨＲ１０９９（＝Ｖ７１１Ｔａｕ）在１９８９年１２月特大能量白光耀发前后的近红外分光光度观测结果，给出该星从２．３－４．１μｍ首次ＣＶＦ低色散光谱，以及耀发前后的变化；计算了同期观测到的子星表面黑子的影响，给出双星黑体近似辐射能谱，并与多波段测光以及ＩＲＡＳ观测作了对比，揭示了该双星有很强的星周物质的２．３μｍ发射带和３．１μｍ波段吸收带特征，本文对可能的星周物质成分和分布亦作了初步讨论。  相似文献