Research lectures, seminars and events
The events listed in this area are research seminars, workshops and lectures hosted by Durham University departments and research institutes. If you are not a member of the University, but wish to enquire about attending one of the events please contact the organiser or host department.
| Sun | Mon | Tue | Wed | Thu | Fri | Sat |
|---|---|---|---|---|---|---|
| April 2013 | June 2013 | |||||
| 1 | 2 | 3 | 4 | |||
| 5 | 6 | 7 | 8 | 9 | 10 | 11 |
| 12 | 13 | 14 | 15 | 16 | 17 | 18 |
| 19 | 20 | 21 | 22 | 23 | 24 | 25 |
| 26 | 27 | 28 | 29 | 30 | 31 | |
Events for 1 May 2013
Centre for Advanced Instrumentation Seminar Programme
Contact claire.whitehill@durham.ac.uk for more information about this event.
Susan Marlow FRSA, Professor of Entrepreneurship, Nottingham University Business School: paper title tbc
Spirituality and Accounting
Pedro Gomez (Bank of England): Technological change and the composition of taxes and public expenditures
About Time Public Lecture Series - 'Keeping Time at Bay: Old Age, Medicine, and Money in Early Modern England'
Contact enquiries.ias@durham.ac.uk for more information about this event.
Professor Tina Beattie: Nothing Really Matters: A Bohemian Rhapsody for a Dead Queen: A Thomist-Lacanian Reflection on the Future of Theology in the Academy
Contact robert.song@durham.ac.uk for more information about this event.
Prof. Alec Ryrie: Devotion in a Polemical Age: Discovering Tolerance in Early Modern Britain
Contact m.j.p.pound@durham.ac.uk for more information about this event.
Bill Sheils: The Clergy and the “free and voluntary present” of 1661: was it?
Contact alec.ryrie@durham.ac.uk for more information about this event.
Dr Mark Oxborrow: Room-temperature solid-state masers based on molecular intersystem crossing (ISC)
Like lasers, masers exploit the quantum mechanical process of stimulated emission to amplifier electromagnetic waves - though at microwave frequencies (i.e. around a few GHz) as opposed to optical ones (several hundreds of THz). Since microwave photons individually carry little energy, a maser can amplifier a weak signal whilst imparting very little deleterious (Schawlow-Townes) shot noise onto it. Masers made out of solid-state gain materials such as ruby were invented in the mid. 1950s. They became key to the success of NASA's deep space network, as used for receiving spectacular images of the rings of Saturn back from its distant Voyager 1 & 2 space probes, as well as supporting other missions (like those to Mars) since. But ruby masers can only operate advantageously at liquid-helium temperatures. This prevented their uptake in a great many applications that could have otherwise taken advantage of their superior noise performance. Compared to semiconductor-based amplifiers, which do work - albeit noisily - at room temperature, masers have languished in the backwaters. In my talk, I shall describe a solid-state maser that does work at room temperature. In contrast to ruby, this new maser's gain medium is an organic mixed molecular crystal, namely p-terphenyl, which is lightly doped with pentacene. Upon photo-exciting the latter species with yellow pump light from a pulsed dye laser, molecular intersystem crossing (ISC) into pentacene's triplet ground state provides a strong population inversion across the upper and lower sub-levels of this state, sufficient for masing at ~1.45 GHz on the TE01δ mode of a high-Q sapphire-loaded cylindrical microwave cavity, with an output (saturation) power of around -10 dBm. As the ISC process provides negative spin temperatures of the order of a few tens of mK, microwaves can in principle be amplified at a residual noise temperature of this same order, even though the maser crystal is at room temperature. In other words: a cryogenic amplifier that isn't. The general prospects of organic masers based on ISC shall be discussed.
