Kirby held a postdoctoral research position at Harvard College Observatory and then became a research physicist at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts. She served as the Associate Director for the Harvard-Smithsonian Center for Astrophysics, heading the Atomic and Molecular Physics Division from 1989 until 2001. She was the Director of the National-Science-Foundation-funded Institute for Theoretical Atomic, Molecular and Optical Physics at Harvard-Smithsonian Center for Astrophysics from 2001 to 2007. Kirby was named as the Executive Officer of the American Physical Society in May 2009, a position she began in July of the same year, replacing Judy Franz. On assuming the role, Kirby said "Having served the Society for well over two decades as a volunteer on a number of committees, the Council and Executive Board, I am excited to be joining the APS leadership team." She added, "I look forward to working with APS staff and the membership to advocate for physics in the public arena and to serve the community of physicists throughout the U.S. and the world." Kirby became the American Physical Society’s chief executive officer in 2015 after a restructuring of the organization.
American Physical Society
Kirby has long-standing links with the American Physical Society, serving in a number of leadership roles at the organization. These include: APS Councilor-at-Large from 1991-1993; Vice-Chair, Chair-Elect, and Chair of the society’s Division of Atomic, and Molecular Physics from 1995-1998; and Divisional Councilor for the Division of Atomic, Molecular and Optical Physics . She was elected to the APS Executive Board in 2005, serving on the board for two years. Kirby has chaired and served on numerous American Physical Society committees, including the Fellowship Committee, the Nominating Committee, the APS Ethics Task Force, and the Committee on Prizes and Awards.
Research
Kirby is a theoretical atomic and molecular physicist. Her research focused on the calculation of atomic and molecular processes important in astrophysics and atmospheric physics. During her career she studied photon absorption of atoms and molecules . She also studied the collision processes between atoms that occur in the atmospheres of astrophysical bodies like brown dwarf stars and planetary nebulae. Kirby later worked on processes for forming ultracold polar molecules using lasers and applying the method to create platforms for quantum computing.