Seaborg remained at the University of California, Berkeley, for post-doctoral research.
He followed Frederick Soddy's work investigating isotopes and contributed to the discovery of more than 100 isotopes of elements.
Using one of Lawrence's advanced cyclotrons, John Livingood, Fred Fairbrother, and Seaborg created a new isotope of iron, iron-59 in 1937.
Iron-59 was useful in the studies of the hemoglobin in human blood.
In 1938, Livingood and Seaborg collaborated (as they did for five years) to create an important isotope of iodine, iodine-131, which is still used to treat thyroid disease. (
Many years later, it was credited with prolonging the life of Seaborg's mother.)
As a result of these and other contributions, Seaborg is regarded as a pioneer in nuclear medicine and is one of its most prolific discoverers of isotopes.

In 1939 he became an instructor in chemistry at Berkeley, was promoted to assistant professor in 1941 and professor in 1945.
University of California, Berkeley, physicist Edwin McMillan led a team that discovered element 93, which he named neptunium in 1940.
In November, he was persuaded to leave Berkeley temporarily to assist with urgent research in radar technology.
Since Seaborg and his colleagues had perfected McMillan's oxidation-reduction technique for isolating neptunium, he asked McMillan for permission to continue the research and search for element 94.
McMillan agreed to the collaboration.
 Seaborg first reported alpha decay proportionate to only a fraction of the element 93 under observation.
The first hypothesis for this alpha particle accumulation was contamination by uranium, which produces alpha-decay particles; analysis of alpha-decay particles ruled this out.
Seaborg then postulated that a distinct alpha-producing element was being formed from element 93.

In February 1941, Seaborg and his collaborators produced plutonium-239 through the bombardment of uranium.
In their experiments bombarding uranium with deuterons, they observed the creation of neptunium, element 93.
But it then underwent beta-decay, forming a new element, plutonium, with 94 protons.
Plutonium is fairly stable, but undergoes alpha-decay, which explained the presence of alpha particles coming from neptunium.
 Thus, on March 28, 1941, Seaborg, physicist Emilio Segrè and Berkeley chemist Joseph W. Kennedy were able to show that plutonium (then known only as element 94) was fissile, an important distinction that was crucial to the decisions made in directing Manhattan Project research.
In 1966, Room 307 of Gilman Hall on the campus at the Berkeley, where Seaborg did his work, was declared a U.S. National Historic Landmark.

In addition to plutonium, he is credited as a lead discoverer of americium, curium, and berkelium, and as a co-discoverer of californium, einsteinium, fermium, mendelevium, nobelium and seaborgium.
He shared the Nobel Prize in Chemistry in 1951 with Edwin McMillan for "their discoveries in the chemistry of the first transuranium elements."
Seaborg remained at the University of California, Berkeley, for post-doctoral research. He followed Frederick Soddy's work investigating isotopes and contributed to the discovery of more than 100 isotopes of elements. Using one of Lawrence's advanced cyclotrons, John Livingood, Fred Fairbrother, and Seaborg created a new isotope of iron, iron-59 in 1937. Iron-59 was useful in the studies of the hemoglobin in human blood. In 1938, Livingood and Seaborg collaborated (as they did for five years) to create an important isotope of iodine, iodine-131, which is still used to treat thyroid disease. (Many years later, it was credited with prolonging the life of Seaborg's mother.) As a result of these and other contributions, Seaborg is regarded as a pioneer in nuclear medicine and is one of its most prolific discoverers of isotopes.
In 1939 he became an instructor in chemistry at Berkeley, was promoted to assistant professor in 1941 and professor in 1945. University of California, Berkeley, physicist Edwin McMillan led a team that discovered element 93, which he named neptunium in 1940. In November, he was persuaded to leave Berkeley temporarily to assist with urgent research in radar technology. Since Seaborg and his colleagues had perfected McMillan's oxidation-reduction technique for isolating neptunium, he asked McMillan for permission to continue the research and search for element 94. McMillan agreed to the collaboration.  Seaborg first reported alpha decay proportionate to only a fraction of the element 93 under observation. The first hypothesis for this alpha particle accumulation was contamination by uranium, which produces alpha-decay particles; analysis of alpha-decay particles ruled this out. Seaborg then postulated that a distinct alpha-producing element was being formed from element 93.
In February 1941, Seaborg and his collaborators produced plutonium-239 through the bombardment of uranium. In their experiments bombarding uranium with deuterons, they observed the creation of neptunium, element 93. But it then underwent beta-decay, forming a new element, plutonium, with 94 protons. Plutonium is fairly stable, but undergoes alpha-decay, which explained the presence of alpha particles coming from neptunium.  Thus, on March 28, 1941, Seaborg, physicist Emilio Segrè and Berkeley chemist Joseph W. Kennedy were able to show that plutonium (then known only as element 94) was fissile, an important distinction that was crucial to the decisions made in directing Manhattan Project research. In 1966, Room 307 of Gilman Hall on the campus at the Berkeley, where Seaborg did his work, was declared a U.S. National Historic Landmark.
In addition to plutonium, he is credited as a lead discoverer of americium, curium, and berkelium, and as a co-discoverer of californium, einsteinium, fermium, mendelevium, nobelium and seaborgium. He shared the Nobel Prize in Chemistry in 1951 with Edwin McMillan for "their discoveries in the chemistry of the first transuranium elements."
Glenn T. Seaborg