怦然 ping¹ jin⁴ {pēng rán}

with a sudden shock, bang etc

怦怦 ping¹ ping¹ {pēng pēng}

1. thumping sound (onom.)
2. to be eager and anxious (to do sth)
3. faithful and upright

怦然心動〔---动〕 ping¹ jin⁴ sam¹ dung⁶ {pēng rán xīn dòng}

palpitating with eagerness to do sth (idiom)