David R Stephens

Title: David R. Stephens: Innovator in Mass Spectrometry

Introduction

David R. Stephens is a notable inventor based in San Jose, CA. He has made significant contributions to the field of mass spectrometry, holding 2 patents that showcase his innovative approaches to analyzing samples.

Latest Patents

One of his latest patents is titled "Method of mass analyzing a sample by use of a quadrupole ion trap." This invention significantly improves mass selection in quadrupole ion trap mass spectrometers by simultaneously trapping ions within the mass range of interest. The method involves scanning the applied RF and DC voltages to sequentially render unstable trapped ions of specific masses, which are then passed out through apertures to a high gain electron multiplier. This process enhances sensitivity and mass resolution, particularly when operating the ion trap at relatively high pressures. The presence of collision gas molecules, such as helium, further improves these parameters. Additionally, the structure of the ion trap is designed for easy disassembly and cleaning, featuring stacked units sealed by O-rings.

Another patent by Stephens is for an "Ionizer having interchangeable ionization chamber." This ionizer is designed to be placed in a vacuum envelope and includes an electron source, ion accelerating and focusing electrodes, and an interchangeable ionization chamber. The chamber allows electrons to enter and form sample ions, which then exit toward the accelerating and focusing electrodes for analysis.

Career Highlights

David R. Stephens has built a successful career at Finnigan Corporation, where he has been instrumental in advancing mass spectrometry technologies. His work has contributed to the development of more sensitive and efficient analytical methods.

Collaborations

Throughout his career, Stephens has collaborated with notable colleagues, including George C. Stafford, Jr. and Paul E. Kelley. These collaborations have further enriched his contributions to the field.

Conclusion

David R. Stephens is a distinguished inventor whose work in mass spectrometry has led to significant advancements in the analysis of samples. His innovative patents reflect his expertise and commitment to improving analytical techniques.