Catálogo de publicaciones - libros

We review a selection of recent technological advances in terahertz frequency time-domain spectroscopy. We discuss the coherent generation of ultra-broadband terahertz radiation using a biased and asymmetrically excited low-temperature-grown GaAs photoconductive (PC) emitter. Using a backward collection method, terahertz radiation with frequency components over 30 THz can be collected, the highest observed for PC emitters. We outline two detection schemes, electro-optic (EO) detection using a ZnTe crystal, and PC-detection using a low-temperaturegrown GaAs PC receiver. The use of the PC receiver provides the timedomain spectroscopy system with a smooth spectral distribution between 0.3 and 7.5 THz, ideal for spectroscopic applications. We illustrate the technological developments with examples of transmission spectroscopy of polycrystalline organic materials. Specifically, we review measurements of the vibrational spectra of polycrystalline purine and adenine over the temperature range 4–290K. A number of well-resolved absorption peaks are observed, which are interpreted as originating from intermolecular vibrational modes mediated by hydrogen bonds. As the temperature is reduced, the observed absorption bands resolve into narrower peaks and some shift towards higher frequencies, which can be explained by the anharmonicity of the vibrational potentials. An empirical expression is given to describe this frequency shift.

Sleep/wake disorders medicine has a relatively brief history. However, since the first sleep/wake disorders center opened in the early 1970s, many people have been assessed and treated. Many of these people were found to have serious sleep/wake disorders that were not even known to exist prior to research conducted at sleep/wake centers. Today, the majority of people with any kind of sleep complaint have a condition which is potentially diagnosable and, more importantly, treatable. Many people can now live better quality lives as a result. The likelihood is for even more improvement of life for countless numbers of people as they too are diagnosed and treated and as research finds out more about these disorders, how they affect our lives, and how they can be treated.

We review a selection of recent technological advances in terahertz frequency time-domain spectroscopy. We discuss the coherent generation of ultra-broadband terahertz radiation using a biased and asymmetrically excited low-temperature-grown GaAs photoconductive (PC) emitter. Using a backward collection method, terahertz radiation with frequency components over 30 THz can be collected, the highest observed for PC emitters. We outline two detection schemes, electro-optic (EO) detection using a ZnTe crystal, and PC-detection using a low-temperaturegrown GaAs PC receiver. The use of the PC receiver provides the timedomain spectroscopy system with a smooth spectral distribution between 0.3 and 7.5 THz, ideal for spectroscopic applications. We illustrate the technological developments with examples of transmission spectroscopy of polycrystalline organic materials. Specifically, we review measurements of the vibrational spectra of polycrystalline purine and adenine over the temperature range 4–290K. A number of well-resolved absorption peaks are observed, which are interpreted as originating from intermolecular vibrational modes mediated by hydrogen bonds. As the temperature is reduced, the observed absorption bands resolve into narrower peaks and some shift towards higher frequencies, which can be explained by the anharmonicity of the vibrational potentials. An empirical expression is given to describe this frequency shift.

Sleep/wake disorders medicine has a relatively brief history. However, since the first sleep/wake disorders center opened in the early 1970s, many people have been assessed and treated. Many of these people were found to have serious sleep/wake disorders that were not even known to exist prior to research conducted at sleep/wake centers. Today, the majority of people with any kind of sleep complaint have a condition which is potentially diagnosable and, more importantly, treatable. Many people can now live better quality lives as a result. The likelihood is for even more improvement of life for countless numbers of people as they too are diagnosed and treated and as research finds out more about these disorders, how they affect our lives, and how they can be treated.