Faculty of Natural Sciences

TY - JOUR

T1 - The primary photo-dissociation dynamics of aqueous formamide and dimethylformamide

AU - Thøgersen, Jan

AU - Weidner, Tobias

AU - Jensen, Frank

N1 - Funding Information: J. T. and T. W. acknowledge the Novo Nordisk Foundation (Facility Grant NanoScat, No. NNF18OC0032628) for funding. Publisher Copyright: © 2022 The Royal Society of Chemistry.

PY - 2022/10

Y1 - 2022/10

N2 - We study the primary dissociation dynamics of aqueous formamide (HCONH2) and dimethylformamide (HCON(CH3)2) induced by photo-excitation at λ = 200 nm. The photolysis is recorded with sub-picosecond time resolution by UV pump-IR probe transient absorption spectroscopy. Formamide dissociates with a quantum yield of Φ(t = 20 ps) = 0.30 ± 0.05, t = 20 ps after the excitation. The rest of the excited formamide molecules return to the ground state within t = 1 ps and vibrationally relax towards equilibrium in t ≈ 10 ps. The only product observed is NH3. NH3 is produced with a yield of Φ(NH3) = 0.23 ± 0.10 on a timescale of τ = 3 ± 1 ps and likely constitutes the dominating product. The CO counter product to NH3 is not observed. Dimethylformamide is photolysed with a quantum yield of Φ(t = 30 ps) = 0.29 ± 0.05, t = 30 ps after the excitation. The photolysis of dimethylformamide produces CO on a time scale of τ ≈ 30 ps. The data indicate that dimethylamine and the N(CH3)2 radical are likely photoproducts.

AB - We study the primary dissociation dynamics of aqueous formamide (HCONH2) and dimethylformamide (HCON(CH3)2) induced by photo-excitation at λ = 200 nm. The photolysis is recorded with sub-picosecond time resolution by UV pump-IR probe transient absorption spectroscopy. Formamide dissociates with a quantum yield of Φ(t = 20 ps) = 0.30 ± 0.05, t = 20 ps after the excitation. The rest of the excited formamide molecules return to the ground state within t = 1 ps and vibrationally relax towards equilibrium in t ≈ 10 ps. The only product observed is NH3. NH3 is produced with a yield of Φ(NH3) = 0.23 ± 0.10 on a timescale of τ = 3 ± 1 ps and likely constitutes the dominating product. The CO counter product to NH3 is not observed. Dimethylformamide is photolysed with a quantum yield of Φ(t = 30 ps) = 0.29 ± 0.05, t = 30 ps after the excitation. The photolysis of dimethylformamide produces CO on a time scale of τ ≈ 30 ps. The data indicate that dimethylamine and the N(CH3)2 radical are likely photoproducts.

KW - Dimethylamines

KW - Dimethylformamide

KW - Formamides

KW - Photolysis

KW - Water

UR - http://www.scopus.com/inward/record.url?scp=85138646813&partnerID=8YFLogxK

U2 - 10.1039/d2cp03166c

DO - 10.1039/d2cp03166c

M3 - Journal article

C2 - 36069146

AN - SCOPUS:85138646813

VL - 24

SP - 24695

EP - 24705

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 40

ER -