Isabella L. Karle, whose experiments elucidating the shapes of molecules contributed crucially to her husband’s Nobel Prize in Chemistry, died on Oct. 3 in Arlington, Va. She was 95.

The cause was a brain tumor, her daughter Louise Karle Hanson said.

Dr. Karle was an expert in bouncing X-rays off crystals to deduce the structure of molecules by observing patterns in the deflected rays. When she and her husband, Jerome Karle, joined the Naval Research Laboratory in Washington in the mid-1940s, the technique was limited and arduous. Scientists did not know how to apply it to most molecules, like large biological ones.

In the 1950s, Jerome Karle, together with Herbert A. Hauptman, a mathematician, developed a technique that could be used for more complex, three-dimensional structures. But they had trouble convincing anyone that it would work.

“My father never actually did a crystal structure in his life,” Ms. Hanson said.

It was her mother who showed that the technique did work.