What are the names of pre-emergent weed control products?

The proper phrase is "pre-emergent herbicide" and it's any herbicide used to prevent the germination and/or emergence of a viable weed species. Compounds such as trifluralin (Treflan brand), S-metolachlor (Dual II Magnum brand), pendimethalin (Prowl brand), and dimethenamid-P (Outlook brand) create a chemical barrier in the top inch or so of the soil to either stop the weed seed from germinating, or make it unable for the weed sprout to break through the soil.