Louis-Victor-Pierre-Raymond , 7th duc de Broglie , ( August 15 , 1892 â `` March 19 , 1987 ) was a French physicist who discovered that electrons have two natures similar to both particles and waves . Louis-Victor-Pierre-Raymond , 7th duc de Broglie , FRS ( dÉ Ë brÉ '' É ; ; 15 August 1892 â `` 19 March 1987 ) was a French physicist and a Nobel laureate .