～たとたん (〜ta totan)
Explanation
Express the moment something happens; 'as soon as', 'the moment', 'the instant'.
Formation
Verb-た form + とたん
Detailed Explanation
The ～たとたん grammar point is used to express that something occurs immediately at the exact moment another action is completed. It can be translated as 'as soon as', 'the moment', or 'the instant' in English. It is attached to the past tense (た-form) of a verb.
Examples
ドアを開けたとたん、猫が逃げ出した。
Doa wo aketa totan, neko ga nigedashita.
As soon as I opened the door, the cat ran away.
電話をかけたとたん、電池が切れた。
Denwa wo kaketa totan, denchi ga kireta.
The moment I made the phone call, the battery died.
雨が降り始めたとたん、みんなが傘をさした。
Ame ga furihajimeta totan, minna ga kasa wo sashita.
The instant it started raining, everyone put up their umbrellas.
彼に会ったとたん、彼の笑顔が消えた。
Kare ni atta totan, kare no egao ga kieta.
As soon as he met me, his smile disappeared.
Grammar content sourced from hanabira.org.