X-ray photoelectron spectroscopy analysis of gold surfaces after removal of thiolated DNA oligomers by ultraviolet/ozone treatment

Well-ordered films of molecular DNA can be formed by the attachment of thiolated DNA oligonucleotides to a supporting gold substrate. The gold substrate represents a significant fraction of the total cost of preparing such films, and it is thus important to determine whether such substrates can be reused. Here, we investigate with X-ray photoelectron spectroscopy the suitability of UV/ozonolysis previously employed to remove alkanethiols from gold, for removing 40-mer, single- and double-stranded synthetic DNA. We find that while UV/O3 can indeed remove thiolated DNA from gold slides, the treatment times required permit the implantation of additional organic contaminants

MUSTANG. First light and current status

MUSTANG is a 90 GHz bolometer camera built for use as a facility instrument on the 100 m Green Bank radio telescope (GBT). MUSTANG has an 8 by 8 focal plane array of transition edge sensor bolometers read out using time-multiplexed SQUID electronics. On the GBT each pixel has an 8" beam size. In one hour we expect to be able to map a 15' square of sky to 0.2 mjy/beam RMS making MUSTANG on the GBT a very competitive instrument capable of a wide range of galactic and extragalactic science. In September 2006 MUSTANG had first light and became the first instrument to use the GBT at 90 GHz. During two months of subsequent testing we showed that MUSTANG behaved as well on the telescope as it did in the lab. Observations were made of many astronomical sources including Saturn and the star forming region W3. We were able to confirm our beam shape and different observing strategies were tested. Procedures were put in place for pointing and focusing and a data analysis pipeline was set up. Several problems were identified during commissioning and are currently being addressed. One of these, excessive 1/f noise, has already been solved and we plan to take our first science observations in late 2007

A 90-GHz bolometer array for the green bank telescope

The Penn Array Receiver (PAR) is a camera designed for rapid, high angular resolution imaging at 90 GHz (3.3 mm). When installed on the 100 m Green Bank Telescope it will have a 32" × 32" field of view and 8" resolution. PAR has an eight by eight planar array of superconducting Transition Edge Sensor bolometers. Currently it is in the commissioning phase and after that it will become a user instrument capable of mapping a 5' × 5' area of sky to a noise level of 40 μ Jy in one hour