William Blaine Richardson III (born November 15, 1947) is an American politician, author, and diplomat who served as the 30th Governor of New Mexico from 2003 to 2011. He was U.S. Ambassador to the United Nations and Energy Secretary in the Clinton administration and has also served as a U.S. Congressman, chairman of the 2004 Democratic National Convention, and chairman of the Democratic Governors Association. In December 2008, he was nominated for the cabinet-level position of Secretary of Commerce in the first Obama administration, but withdrew a month later as he was investigated for possible improper business dealings in New Mexico. Although the investigation was later dropped, it was seen to have damaged Richardson's career, as his second and final term as New Mexico governor concluded.

With the end of the Clinton administration in January 2001, Richardson took on a number of different positions. He was an adjunct professor at Harvard University's Kennedy School of Government and a lecturer at the Armand Hammer United World College of the American West. In 2000, Bill Richardson was awarded a United States Institute of Peace Senior Fellowship. He spent the next year researching and writing on the negotiations with North Korea and the energy dimensions of U.S. relations. In 2011, Richardson was named a senior fellow at the Baker Institute of Rice University.  Richardson also joined Kissinger McLarty Associates, a "strategic advisory firm" headed by former Secretary of State Henry Kissinger and former Clinton White House chief of staff Mack McLarty, as Senior Managing Director. From February 2001 to June 2002, he served on the board of directors of Peregrine Systems, Inc. He also served on the corporate boards of several energy companies, including Valero Energy Corporation and Diamond Offshore Drilling. He withdrew from these boards after being nominated by the Democratic Party for governor of New Mexico, but retained considerable stock holdings in Valero and Diamond Offshore. He would later sell these stocks during his campaign for President in 2007, saying he was "getting questions" about the propriety of these holdings, especially given his past as energy secretary, and that it had become a distraction.  Richardson is on the board of directors of the National Institute for Civil Discourse (NICD), which was created after the 2011 Tucson shooting that left 6 dead and 13 wounded, including Congresswoman Gabrielle Giffords.

Answer the following question by taking a quote from the article: What years of his life did was he a professor?
With the end of the Clinton administration in January 2001,