2016A&A...596L...1C


C.D.S. - SIMBAD4 rel 1.7 - 2020.06.04CEST14:19:01

2016A&A...596L...1C - Astronomy and Astrophysics, volume 596, L1-1 (2016/12-1)

Trans-cis molecular photoswitching in interstellar space.

CUADRADO S., GOICOECHEA J.R., RONCERO O., AGUADO A., TERCERO B. and CERNICHARO J.

Abstract (from CDS):

As many organic molecules, formic acid (HCOOH) has two conformers (trans and cis). The energy barrier to internal conversion from trans to cis is much higher than the thermal energy available in molecular clouds. Thus, only the most stable conformer (trans) is expected to exist in detectable amounts. We report the first interstellar detection of cis-HCOOH. Its presence in ultraviolet (UV) irradiated gas exclusively (the Orion Bar photodissociation region), with a low trans-to-cis abundance ratio of 2.8±1.0, supports a photoswitching mechanism: a given conformer absorbs a stellar photon that radiatively excites the molecule to electronic states above the interconversion barrier. Subsequent fluorescent decay leaves the molecule in a different conformer form. This mechanism, which we specifically study with ab initio quantum calculations, was not considered in Space before but likely induces structural changes of a variety of interstellar molecules submitted to UV radiation.

Abstract Copyright: © ESO, 2016

Journal keyword(s): astrochemistry - line: identification - ISM: clouds - ISM: molecules - photon-dominated region (PDR)

Status at CDS:  

Simbad objects: 10

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Number of rows : 10

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 Barnard 1 MoC 03 33 16.3 +31 07 51           ~ 253 0
2 [HKM99] B1-bW PoC 03 33 20.0 +31 07 20           ~ 7 0
3 [HKM99] B1-b cor 03 33 20.32 +31 07 21.5           ~ 155 0
4 [HRF2005] 3 PoC 03 33 21.3 +31 07 27           ~ 59 0
5 [KJD2006] SMM J033335+31075 PoC 03 33 21.3 +31 07 28           ~ 72 0
6 NAME Perseus Cloud SFR 03 35.0 +31 13           ~ 1051 0
7 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 1987 1
8 NAME Orion Core ? 05 35 14.5 -05 22 30           ~ 174 0
9 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 710 0
10 NAME ORI MOL CLOUD MoC 05 56 -01.8           ~ 842 1

    Equat.    Gal    SGal    Ecl

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2020.06.04-14:19:01

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