▁chem istry , ▁chemical ▁physics , ▁appar atus ▁construction ▁and ▁electron ics . ▁In ▁addition ▁to ▁his ▁core ▁research ▁interests , ▁Bak ▁also ▁published ▁and ▁continued ▁to ▁investigate ▁related ▁subjects ▁such ▁as ▁inf ra red ▁spect ro sc opy , ▁nuclear ▁magnetic ▁reson ance ▁spect ro sc opy ▁( where ▁he ▁was ▁Dan ish ▁pione er ) ▁and ▁the ▁spect ra ▁of ▁vol atile ▁py ro ly s is ▁products ▁which ▁later ▁proved ▁to ▁be ▁of ▁particular ▁importance ▁for ▁chem istry ▁and ▁ast ro - chem istry . ▁ ▁Re putation ▁The ▁Dan ish ▁Chem ist ▁and ▁J or ck ▁Prize ▁winner ▁K j eld ▁R asm ussen ▁described ▁his ▁view ▁of ▁Bak ▁in ▁his ▁fare well ▁remarks ▁from ▁the ▁University ▁of ▁C open hagen : ▁" My ▁occupation ▁with ▁inf ra red ▁spect ro sc opy ▁lead ▁to ▁teaching ▁M ole cular ▁Spect ro sc opy . ▁It ▁was ▁done ▁in ▁collaboration ▁with ▁this ▁subject ' s ▁N est or ▁in ▁Den mark , ▁B ør ge ▁Bak , ▁who ▁was ▁professor ▁at ▁the ▁University ▁of ▁C open hagen ▁and ▁external ▁lect urer ▁at ▁Poly te kn isk ▁L æ re anstalt ▁which ▁is ▁the ▁old ▁name ▁of ▁the ▁Techn ical ▁University . ▁B ør ge ▁Bak ▁was ▁ste pping ▁down , ▁being ▁ill , ▁and ▁I ▁soon ▁took ▁over ▁the ▁teaching , ▁in ▁the ▁beginning ▁with ▁Bak ▁as ▁c ensor . ▁A ▁t ough ▁one , ▁both ▁to ▁me ▁and ▁to ▁the ▁students ." ▁ ▁W art ime ▁Activ ities ▁B