Chemical Evolution in Protoplanetary Disks

To my family, who have supported me throughout this long process. And to Katie, I wouldn’t have made it without you. ii ACKNOWLEDGMENTS I would not have been able to complete this dissertation without support from many colleagues. I am pleased to have this opportunity to acknowledge their contri-butions. First and foremost I would like to thank my advisor, Ted Bergin. He worked tirelessly with me along the way to track down bugs, decipher results and generally make sure that my work was the best that it could be. When I was stuck on an issue, a conversation with Ted immediately clarified how to solve the problem and how to move forward. I learned a huge amount from him, both about astronomy and about how to approach and solve problems. He also acted as a mentor, providing important support and guidance in my career decisions. I also would like to thank my committee members, Sushil Atreya, Nuria Calvet, Chuck Cowley and Lee Hartmann for their feedback and advice along the way. Their comments were critical in shaping this work. All of them were very generous with their time and willing to discussing any issues that arose during my research. The work presented here could not have been completed without the support an