Clear up the puzzle to find the chemist known for cleaning up the air

Solve this wordoku in the same way as a sudoku with letters instead of numbers (each of the nine letters in each row, column and nine-square cell). Once solved, one of the overall diagonals can be rearranged into the surname of an Italian chemist, known for their work on environmental pollutants.

This week’s letters are: A C E F H I M S T