Low Voltage Scanning Electron Microscopy Research Paper

Low Voltage Scanning Electron Microscopy - Research Paper Example Working Principles of Scanning Electron Microscopy (SEM) Scanning electron microscopes (SEMs) are microscopes, which produce sample images by scanning the samples using a beam of focused electrons. The focused beam of electrons interacts with electrons within the sample to produce differing signal strengths that can be detected by a secondary electron detector. The focused electrons hit the sample surface, where they either get reflected as back-scattered electrons (BSE) due to inelastic scattering or cause an emission of electrons from the sample surface as secondary electrons (SE) due to elastic scattering (Lyman, 1990). The SE are emitted from the k-orbitals of the sample once the electrons in the beam hit them in a strong enough way that displaces them from the orbital. Both BSE and SE show different properties of the sample material, which commonly includes composition and topography (Boyes, 2000). The focused beam of electrons is scanned by raster scanning and position of the b eam is combined with the signal from the BSE and SE to develop an image. This type of microscopic observation can attain resolutions that are better than a nanometer. The focused beam used in SEM is produced by thermionic means from an electron gun consisting of a cathode made of tungsten. Tungsten is preferable because of its relatively lower vapor pressure and high melting point. Additionally, it is cost-effective because it is relatively cheap. The produced beam passes through two lenses that focus it onto the specimen. The energy of the beam ranges from 0.2 keV to 40 keV depending on the design of the microscope. The focus offers a spot diameter of approximately 0.4 nanometers to 5 nanometers (Joy & Carolyn, 1996). On reaching the final lenses in the column the beam is deflected by a pair of deflecting plates, which deflect it in two planes (X, Y planes) so as to create a raster scan area that is rectangular over the sample’s surface (Asmar et al., 2004). The interaction of beam electrons and the sample make the electrons lose energy through repeated random scattering, which occurs near the surface or much deeper depending on the projection energy in keV. This interaction volume from which energy is released in form of electrons to create the image is known as the interaction volume. The interaction volume is determined by the landing energy of the electrons from the projected beam as well as density and atomic number of the material under observation as the sample. Technically, the differences between HVEM and LVEM are a result of differences in landing energy determined by the electron accelerating voltage. The acquired signals are detected and amplified to develop images. The differences of detected signals are represented by variations in brightness on the visual display. The resultant image is thus a representative of electron energy emitted from the sample’s surface through inelastic and elastic scattering. The Unique Nature of Low volt age scanning electron microscopy (LVSEM) According to Joy and Carolyn (1996), even prior to practical use of scanning electron microscopes, it had been recognized that scanning at low electron accelerating voltage (

The accidental investment and Mans search for meaning compared Essay

The accidental investment and Mans search for meaning compared - Essay Example These themes revolve around ethics, morality, values and motivation. Ethics is the differentiation of good and bad and so is morality. Morality however has an aspect that revolves around the background the individual or people have been brought up in and the morals that were instilled in such individuals. It is therefore not a wonder then that in the first book which solely deals with bankers, the author describes in detail how some bankers shamelessly and in most cases surreptitiously swindle their clients finances by lying about investments and especially those made through the internet. The author who was also in that business but later due to the lack of ethics and morality of the colleagues left explains how those bankers are self-centered thinking only about their future and not of those clients. This may be termed as a lack of morality, self-value and even ethics. The theme of motivation in this book becomes evident where it the motivations of the bankers to make ends meet and avoid having a poor future that make them swindle and lie to clients about investments. The same can be said about the second book whose concept of lack of morality, values and ethics revolves around the Nazi soldiers whose lack of the above mentioned themes led to them treating the Jews inhumanely and subjecting them to unbearable torture. It is this torture that made the author of the book decide to introduce a motivator through counseling the rest of the prisoners to keep their hopes and dreams alive and avoid them losing touch and giving up in life despite them being in the concentration camp. In the first book about investment, the author gives first-hand experience of what really goes on in the investment business that the rest of the population do not know are simply too ignorant to understand. The ethics and morality by bankers in the investment business has simply evolved from being that based on truth and deep care for the client to that of making money and generating rev enue regardless of how they will do it. Their values are not in customer satisfaction or benefit like it used to be the case in other previous decades, they simply think about themselves and their future which is uncertain and hence will fleece the innocent investors of their money without flinching an eye. Their motivation relies on internet and it superb working to connect many investors and at the same time remain faceless hence avoiding feelings of guilt in the end. The other book â€Å"Man’s search of meaning† is simply a personal experience about the author’s time spent in Nazi’s concentration camp, the hardships they faced, the inhumane treatment, the lack of morals and values by the guards running the camps and in the end the motivation behind survival in the camps and not giving up hope in spite of all the mistreatment. The theme of the first part of the book is about ethics and morality and how the guards in the concentration camp just like the bankers in the above book think about only themselves and hence step down harder on the rest of the people to achieve their goals and objectives at the end of the day. The motivation in the second part where logo therapy is employed by the author in a bid to keep alive and survive all that is interconnected with the motivation behind the banker’s use of internet to benefit themselves and feel less guilt or sad emotions for what they are doing. 2 How do the themes connect with my own ethics, values, interests and motivators? Ethics enable a person differentiate between the good and the bad and therefore make one avoid or correct the things that are deemed bad by the individual or society and concentrate on the good or work towards the good. The