Find the French chemist’s elemental surname in this sudoku-style puzzle

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 a French chemist’s surname. The name consists of five element symbols in sequence: metal–gas–metal–gas–metal.

This week’s letters are: A E F I M N S T U