The preparation, characterization and tribological properties of TA-C : H deposited using an electron cyclotron wave resonance plasma beam source

A compact electron cyclotron wave resonance (ECWR) source has been developed for the high rate deposition of hydrogenated tetrahedral amorphous carbon (ta-C:H). The ECWR provides growth rates of up to 900 Å/min over a 4″ diameter and an independent control of the deposition rate and ion energy. The ta-C:H was deposited using acetylene as the source gas and was characterized in terms of its sp3 content, mass density, intrinsic stress, hydrogen content, C-H bonding, Raman spectra, optical gap, surface roughness and friction coefficient. The results obtained indicated that the film properties were maximized at an ion energy of approximately 167 eV, corresponding to an energy per daughter carbon ion of 76 eV. The relationship between the incident ion energy and film densification was also explained in terms of the subsurface implantation of carbon ions into the growing film.

Amorphous carbon-silicon alloys prepared by a high plasma density source

The addition of silicon to hydrogenated amorphous carbon can have the advantageous effect of lowering the compressive stress, improving the thermal stability of its hydrogen and maintaining a low friction coefficient up to high humidity. Most experiments to date have been on a-C1-xSix:H alloys deposited by RF plasma enhanced chemical vapour deposition (PECVD). This method gives alloys with considerable hydrogen content and only moderate hardness. Here, we use a high plasma density source, the electron cyclotron wave resonance (ECWR) source, to prepare films with a high deposition rate. The composition and bonding in the alloys is determined by XPS, visible and UV Raman and FTIR spectroscopy. We find that it is possible to produce hard, low stress, low friction, almost humidity insensitive a-C1-xSix:H alloys with a good optical transparency and a band gap over 2 eV.

Nitrogen incorporation into tetrahedral hydrogenated amorphous carbon

Structural changes induced by the incorporation of nitrogen into ta-C : H films have been studied by Electron Energy Loss Spectroscopy, X-Ray Photoelectron Spectroscopy, Fourier Transformed Infrared Spectroscopy and Ultraviolet-Visible Spectroscopy. ta-C:H films have been synthesised using a low pressure Electron Cyclotron Wave Resonance (ECWR) source which provides a plasma beam with a high degree of ionisation and dissociation. Nitrogen was incorporated by adding N2 to the C2H2 plasma used for the deposition of ta-C : H films. The N/C atomic ratio in the films rises rapidly until the N2/C2H2 gas ratio reaches three, and then increases more gradually, while the deposition rate decreases steeply. Chemical sputtering of the forming films and the formation of molecular nitrogen within the films limit the maximum nitrogen content to about N/C = 0.6. For low nitrogen content the films retain their diamond-like properties, however as N/C atomic ratio increases, a polymeric-like material is formed, with >C=N- structures and terminating C=N and NH groups that decrease the connectivity of the network.

Investigation of Fundamental Processes Governing Secondary Organic Aerosol Formation in Laboratory Chambers

Our understanding of the processes and mechanisms by which secondary organic aerosol (SOA) is formed is derived from laboratory chamber studies. In the atmosphere, SOA formation is primarily driven by progressive photooxidation of SOA precursors, coupled with their gas-particle partitioning. In the chamber environment, SOA-forming vapors undergo multiple chemical and physical processes that involve production and removal via gas-phase reactions; partitioning onto suspended particles vs. particles deposited on the chamber wall; and direct deposition on the chamber wall. The main focus of this dissertation is to characterize the interactions of organic vapors with suspended particles and the chamber wall and explore how these intertwined processes in laboratory chambers govern SOA formation and evolution.

A Functional Group Oxidation Model (FGOM) that represents SOA formation and evolution in terms of the competition between functionalization and fragmentation, the extent of oxygen atom addition, and the change of volatility, is developed. The FGOM contains a set of parameters that are to be determined by fitting of the model to laboratory chamber data. The sensitivity of the model prediction to variation of the adjustable parameters allows one to assess the relative importance of various pathways involved in SOA formation.

A critical aspect of the environmental chamber is the presence of the wall, which can induce deposition of SOA-forming vapors and promote heterogeneous reactions. An experimental protocol and model framework are first developed to constrain the vapor-wall interactions. By optimal fitting the model predictions to the observed wall-induced decay profiles of 25 oxidized organic compounds, the dominant parameter governing the extent of wall deposition of a compound is identified, i.e., wall accommodation coefficient. By correlating this parameter with the molecular properties of a compound via its volatility, the wall-induced deposition rate of an organic compound can be predicted based on its carbon and oxygen numbers in the molecule.

Heterogeneous transformation of δ-hydroxycarbonyl, a major first-generation product from long-chain alkane photochemistry, is observed on the surface of particles and walls. The uniqueness of this reaction scheme is the production of substituted dihydrofuran, which is highly reactive towards ozone, OH, and NO3, thereby opening a reaction pathway that is not usually accessible to alkanes. A spectrum of highly-oxygenated products with carboxylic acid, ester, and ether functional groups is produced from the substituted dihydrofuran chemistry, thereby affecting the average oxidation state of the alkane-derived SOA.

The vapor wall loss correction is applied to several chamber-derived SOA systems generated from both anthropogenic and biogenic sources. Experimental and modeling approaches are employed to constrain the partitioning behavior of SOA-forming vapors onto suspended particles vs. chamber walls. It is demonstrated that deposition of SOA-forming vapors to the chamber wall during photooxidation experiments can lead to substantial and systematic underestimation of SOA. Therefore, it is likely that a lack of proper accounting for vapor wall losses that suppress chamber-derived SOA yields contribute substantially to the underprediction of ambient SOA concentrations in atmospheric models.

Write-once medium with Fe-Doped BiOx thin films for blue laser recording

Fe:BiOx films are fabricated on K9 glass substrates by rf-magnetron sputtering of a BiFeO target under argon atmosphere with increasing sputtering power from 80 to 200 W at room temperature. It is found that the thin films grown at the sputtering power of 160W can be formed at an appropriate deposition rate and have an improved surface morphology. The XPS result reveals that the films investigated are comprised of Bi, Fe and O elements. A typical XRD pattern shows that no phase transition occurs in the films up to 400 degrees C. The results of the blue laser recording test demonstrate that the Fe:BiOx films have good writing sensitivity for blue laser beam (406.7 nm) and good stability after reading 10000 times. The recording marks of 200nm or less are obtained. These results indicate that the introduction of Fe into BiOx films can reduce the mark size and improve the stability of the films.

River Lune salmon action plan March 1997. Draft Copy.

The River Lune was at one time one of the best salmon fisheries in England and Wales with very high catches to both rods and netsmen. During the 1960's, the stock was decimated by the disease Ulcerative Dermal Necrosis which caused a dramatic reduction in catches. Catches have not recovered to pre-disease levels. The target egg deposition rate for the River Lune system which should produce the maximum number of surplus fish returning to the system has been determined at 13.8 million eggs. This will require 4,779 adult salmon to survive to successfully spawn. Under current rates of exploitation, the target egg deposition will occur at a declared rod catch of 1,974 salmon and a net catch of 2,627 salmon. Two automatic fish counters are in operation on the river system. Data from these suggest that, within the measures of compliance, the river has met it's target egg deposition for the last 3 years.

双源共蒸法制备非均匀膜的模型分析

探讨了双源共蒸法制备非均匀薄膜的堆积模型，并给出了非均匀膜的沉积速率与两种膜料沉积速率的关系．当两种膜料的沉积单分子大小近似相等或者小分子沉积速率远大于大分子时，可以近似认为混合介质膜的沉积速率等于两种膜料的沉积速率之和；当两种膜料的沉积单分子大小不满足近似相等且两种膜料的沉积速率可比较时，非均匀膜的沉积速率不能简单地用两种膜料的沉积速率之和来近似，它将随两种膜料沉积单分子的大小不同和沉积速率比不同按照不同的规律变化，并在文中给出了不同情况下的非均匀膜的沉积速率变化规律。

共蒸法制备非均匀膜的速率控制分析

渐变折射率薄膜，又称为非均匀膜。利用德鲁德理论分析了混合介质膜的介电常量与各个膜料的介电常量之间的关系，介绍了共蒸法制备非均匀膜的制备机理。对混合膜的沉积速率为两种膜料的沉积速率之和的情况，分别从两种膜料的单分子体积是否相等和总的沉积速率是否为常数两个方面，探讨了双源共蒸法制备的非均匀膜的折射率分布规律与膜料的沉积速率之间的关系，并给出了几种常见的折射率分布如线性变化、正弦变化、指数变化和双曲变化规律的膜料沉积速率表达式。最后以混合介质膜的总沉积速率为常数、折射率按照线性变化为例进行了说明。

线性共蒸法制备渐变折射率薄膜的光学特性分析

利用德鲁德理论和洛伦兹一洛伦茨理论，从介电常数分析人手，探讨了混合介质膜的折射率表达式，给出利用双源共蒸法镀制的渐变折射率薄膜在混合介质膜的总沉积速率恒定、两种膜料的单分子大小近似相等和沉积速率均为线性变化时的折射率表达式；从正变和负变、单周期和多周期、不同的周期数和不同的单周期厚度几个方面对渐变折射率薄膜的光学特性进行了模拟分析和讨论；对渐变折射率薄膜的实现、应用以及实验制备中有待进一步解决和处理的问题进行了讨论。

德鲁德分布非均匀膜的光学特性模拟分析

从德鲁德理论出发，对多元共蒸法镀制的非均匀膜的折射率分布与沉积速率的关系进行了探讨；然后利用计算机辅助模拟，对德鲁德分布非均匀光学薄膜，从单周期和多周期、正变和负变、完整周期和存在半周期几个方面对其光学特性进行了系统分析．研究发现：其透射率的极小值和周期数的关系遵从周期数的三次多项式衰减规律，不同规律的德鲁德分布非均匀膜可用来设计不同功能的滤光片．

The effect of diffusion and overhangs/vacancies on the microstructure of zig-zag thin film

Basing on some growth models of thin film, we have investigated the growth mechanism of glancing angle deposition (GLAD) film. The simulation verifies that the overhangs/vacancies also contribute to the columnar growth as well as the self-shadowing effect for GLAD thin film. Besides, we have studied the effect of the deposition rate, surface and bulk diffusions on the microstructure of thin film using the time-dependent Monte Carlo method. The results show that the surface and bulk diffusions can significantly enhance the packing density of thin film in GLAD growth, and the increase of the deposition rate induce the moderate decrease of the packing density. (c) 2006 Elsevier B.V. All rights reserved.

三硼酸锂晶体上1064 nm, 532 nm, 355 nm三倍频增透膜的设计

采用矢量法设计了三硼酸锂晶体上1064 nm、532 nm和355 nm三倍频增透膜,结果表明1064 nm、532 nm和355 nm波长的剩余反射率分别为0.0017％、0.0002％和0.0013％。根据误差分析,薄膜制备时沉积速率精度控制在＋5.5％时,1064 nm、532 nm和355 nm波长的剩余反射率分别增加至0.20％、0.84％和1.89％。当材料折射率的变化控制在＋3％时,1064 nm处的剩余反射率增大为0.20％,532 nm和355 nm处分别达0.88％和0.24％。与薄膜

沉积速率对热舟蒸发LaF3薄膜性能的影响

用热舟蒸发方法在不同的沉积速率下制备了LaF3单层膜,并对部分单层膜进行了真空退火。分别采用X射线衍射(XRD),Lambda 900 光谱仪和355 nm Nd∶YAG脉冲激光测试了薄膜的晶体结构、透射光谱和激光损伤阈值(LIDT),并通过透射光谱计算得到样品的折射率和消光系数。实验结果表明,增大沉积速率有利于LaF3薄膜的结晶和择优生长,可以提高薄膜的致密性和折射率,但薄膜的抗激光损伤能力有所下降;沉积速率太大,又会恶化薄膜的结晶性能,同时薄膜中产生大量孔洞,薄膜的机械强度降低,导致薄膜的折射率减小和

LiB3O5晶体上四倍频增透膜设计

采用矢量法设计了三硼酸锂（LiB3O5，LBO）晶体上1064nm、532nm、355nm和266nm四倍频增透膜．结果表明，在1064nm、532nm、355nm和266nm波长的剩余反射率分别为0．0019％、0．0031％、0．0061％和0．0047％．根据容差分析，薄膜制备时沉积速率准确度控制在＋6．5％时，基频、二倍频、三倍频和四倍频波长的剩余反射率分别增加至0．24％、0．92％、2．38％和4．37％．当薄膜材料折射率的变化控制在＋3％时，1064nm波长的剩余反射率增大为0．18％，532nm、355nm和266nm波长分别达0．61％，0．59％，0．20％．与薄膜物理厚度相比，膜层折射率对剩余反射率的影响大．对膜系敏感层的分析表明，在1064nm和266nm波长，从入射介质向基底过渡的第二层膜厚度变化对剩余反射率的影响最大，其次是第一膜层．在532nm和355nm波长，从入射介质向基底过渡的第一和第四膜层是该膜系的敏感层．误差分析也表明，薄膜材料的色散对特定波长的剩余反射率具有明显影响，即1064nm、532nm、355nm和266nm波长的剩余反射率分别增加至0．30％、0．23％、0．58％和3．13％．

Characterization of LaF3 coatings prepared at different temperatures and rates

LaF3 thin films were prepared by thermal boat evaporation at different substrate temperatures and various deposition rates. X-ray diffraction (XRD), Lambda 900 spectrophotometer and X-ray photoelectron spectroscopy (XPS) were employed to study crystal structure, transmittance and chemical composition of the coatings, respectively. Laser-induce damage threshold (LIDT) was determined by a tripled Nd:YAG laser system with a pulse width of 8 ns. It is found that the crystal structure became more perfect and the refractive index increased gradually with the temperature rising. The LIDT was comparatively high at high temperature. In the other hand, the crystallization status also became better and the refractive index increased when the deposition rate enhanced at a low level. If the rate was super rapid, the crystallization worsened instead and the refractive index would lessen greatly. On the whole, the LIDT decreased with increasing rate. (C) 2007 Elsevier B.V. All rights reserved.