Such "exclamations" have their very own Chinese character, but are rarely utilized in formal written paperwork. Rather, they're found in movie subtitles, songs lyrics, informal literature and on net forums.

List of Chinese Exclamations
    拼音 (pīnyīn)  Definition
啊 ā  surprise,praise
啊 á  questioning
啊 ǎ disbelief
啊 à

answer, understanding, surprise, praise
哎/嗳 āi dissatisfaction, reminding
哎呀 āiyā  surprise, complaining, impatience
哎哟 āiyō surprise, agony
哎 ái emphasis
嗳/哎 ài regret
哈 hā  triumphant, satisfaction
哈哈 hāhā triumphant, satisfaction
咳 hāi sadness; regret; surprise
嘿/嗨 hēi  drawing attention; showing pride; surprise
呵/嗬 hē surprise
哼 hēng dissatisfaction; disbelief
嗯/唔 én  querry
嗯 ěn out of expectation
嗯 èn answer
喔/噢 ō  understanding
喔/噢唷 ōyō surprise
哦 ó half belief half doubt
哦/喔 ò understanding 
呸 pēi discarding; scolding
哇 wā/wǎ surprise
哟 yō  slight surprise
嗳/哎 ǎi  disagreement; denying