Hydrogen Isotopic Substitution Studies of the 2165 Wavenumber (4.62 Micron) “XCN” Feature Produced by Ion Bombardment

Palumbo, M. E.; Pendleton, Y. J.; Strazzulla, G.

doi:10.1086/317061

Cited by 50 publications

(37 citation statements)

References 21 publications

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“…In all photolysis warm-up experiments this band disappears quickly above 250 K (dÏHendecourt et al 1986 ; Allamandola et al 1988 ;Bernstein et al 1995). A thorough discussion of this feature is presented in Demyk et al (1998), Pendleton et al (1999), Palumbo et al (2000aPalumbo et al ( , 2000b, and Bernstein et al (2000).…”

Section: Infrared Propertiesmentioning

confidence: 92%

The Organic Refractory Material in the Diffuse Interstellar Medium: Mid‐Infrared Spectroscopic Constraints

Pendleton

Allamandola

2002

ASTROPHYS J SUPPL S

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341

408

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This is an analysis of the 4000È1000 cm~1 (2.5È10 km) region of the spectrum of di †use interstellar medium (DISM) dust compared with the spectra of 13 materials produced in the laboratory which serve as analogs to the interstellar material. The organic signatures of extragalactic dust, carbonaceous chondritic material, and E. coli bacteria are also presented because these have been discussed in the literature as relevant to the di †use interstellar medium. Spectral analysis of the DISM allows us to place signiÐ-cant constraints on the applicability of proposed candidate materials. The spectra of candidate materials are evaluated using four spectral characteristics based on the interstellar data : (i) comparisons of the proÐle and subpeak positions of the 2940 cm~1 (3.4 km) aliphatic CH stretching-mode band, (ii) the ratio of the optical depth (O.D.) of the aliphatic CH stretch to the O.D. of the OH stretch near 3200 cm~1 (3.1 km), (iii) the ratio of the O.D. of the aliphatic CH stretch to the O.D. of the carbonyl band near 1700 cm~1 (5.9 km), and (iv) the ratio of the O.D. of the aliphatic CH stretch feature to the O.D. of the CH deformation modes near 1470 cm~1 (6.8 km) and 1370 cm~1 (7.25 km). We conclude that the organic refractory material in the di †use interstellar medium is predominantly hydrocarbon in nature, possessing little nitrogen or oxygen, with the carbon distributed between the aromatic and aliphatic forms. Long alkane chains with n much greater than 4 or 5 are not major constituents H 3 Cw(CH 2 ) n w of this material. Comparisons to laboratory analogs indicate the DISM organic material resembles plasma processed pure hydrocarbon residues much more so than energetically processed ice residues. This result is consistent with a birth site for the carrier of the 3.4 km band in the outÑow region of evolved carbon stars. The organic material extracted from the Murchison carbonaceous meteorite and the spectrum of E. coli bacteria reveal spectral features in the 5È10 km region that are absent in the DISM. Although the presence of unaltered circumstellar components in the Murchison meteorite has been established through several lines of evidence, it is unclear whether or not the aliphatic component which gives rise to the 3.4 km band is in that category. Considering the complete 2È10 km wavelength region, there is no spectral evidence for a biological origin of the 3.4 km interstellar absorption band. The similarity of the aliphatic CH stretch region of dust from our own Galaxy compared with that of distant galaxies suggests that the organic component of the ISM is widespread and may be an important universal reservoir of prebiotic organic carbon.

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Section: Infrared Propertiesmentioning

confidence: 92%

The Organic Refractory Material in the Diffuse Interstellar Medium: Mid‐Infrared Spectroscopic Constraints

Pendleton

Allamandola

2002

ASTROPHYS J SUPPL S

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341

408

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“…In this way, surface chemistry experiments (Collings et al 2003;Watanabe & Kouchi 2002a;Watanabe et al 2003), UV photolysis (Gerakines et al 1996;Watanabe & Kouchi 2002b) and ion irradiation (radiolysis, e.g., Hudson & Moore 1999Palumbo & Strazzulla 1993;Palumbo et al 2000;Baragiola et al 2003) give us information about the basic processes of ice mantle formation, adsorption, diffusion, desorption and reaction pathways.…”

Section: Astrophysical Considerationsmentioning

confidence: 99%

Hydrogen peroxide production by ion irradiation of thin water ice films

Gomis

Leto

Strazzulla

2004

A&A

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Abstract. In this paper we present the results of new experiments on ion irradiation of water ice performed on thin films to study the synthesis of the hydrogen peroxide molecule and discuss the possibility of detecting it in icy mantles on interstellar grains. The used experimental technique has been in situ infrared spectroscopy. We have irradiated thin films (i.e. the ice thickness was smaller than the penetration depth of the used ion) with three different ions, namely 200 keV of H + and He + and 400 keV of Ar ++ . The experiments were carried out at temperatures of 16 and 77 K. We have found that hydrogen peroxide is produced by all of the different ions at both temperatures. The detection of such a molecule has been possible from the study of its infrared feature centered at about 2850 cm −1 (3.5 µm). The obtained results also show that the produced H 2 O 2 /H 2 O(%) ratio is greater for the heaviest ion (∼6% for the case of Ar ++ ) and that H + is the ion that produces the smallest quantity (∼1%). These upper limits in the production of hydrogen peroxide constrain the quantity of H 2 O 2 that can be formed after bombardment by cosmic particles on icy mantles of grains in the interstellar medium.

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“…Experimental studies using isotopic substitution proved unequivocally that the carrier of the laboratory feature is OCN − (Schutte & Greenberg 1997;Bernstein et al 2000;Novozamsky et al 2001;Palumbo et al 2000). Despite this assigment, alternative identifications of the interstellar feature are still debated (Pendleton et al 1999).…”

Section: Introductionmentioning

confidence: 99%

A 3–5 $\mathsf{\mu}$m VLT spectroscopic survey of embedded young low mass stars II

Broekhuizen

Pontoppidan

Fraser

et al. 2005

A&A

126

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Abstract. The 4.62 µm (2164.5 cm −1 ) "XCN" band has been detected in the M-band spectra of 34 deeply embedded young stellar objects (YSO's), observed with high signal-to-noise and high spectral resolution with the VLT-ISAAC spectrometer, providing the first opportunity to study the solid OCN − abundance toward a large number of low-mass YSO's. It is shown unequivocally that at least two components, centred at 2165.7 cm −1 (FWHM = 26 cm −1 ) and 2175.4 cm −1 (FWHM = 15 cm −1 ), underlie the XCN band. Only the 2165.7-component can be ascribed to OCN − , embedded in a strongly hydrogen-bonding, and possibly thermally annealed, ice environment based on laboratory OCN − spectra. In order to correct for the contribution of the 2175.4-component to the XCN band, a phenomenological decomposition into the 2165.7-and the 2175.4-components is used to fit the full band profile and derive the OCN − abundance for each line-of-sight. The same analysis is performed for 5 high-mass YSO's taken from the ISO-SWS data archive. Inferred OCN − abundances are ≤0.85% toward low-mass YSO's and ≤1% toward high-mass YSO's, except for W33 A. Abundances are found to vary by at least a factor of 10-20 and large source-to-source abundance variations are observed within the same star-forming cloud complex on scales down to 400 AU, indicating that the OCN − formation mechanism is sensitive to local conditions. The inferred abundances allow quantitatively for photochemical formation of OCN − , but the large abundance variations are not easily explained in this scenario unless local radiation sources or special geometries are invoked. Surface chemistry should therefore be considered as an alternative formation mechanism.

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Hydrogen Isotopic Substitution Studies of the 2165 Wavenumber (4.62 Micron) “XCN” Feature Produced by Ion Bombardment

Cited by 50 publications

References 21 publications

The Organic Refractory Material in the Diffuse Interstellar Medium: Mid‐Infrared Spectroscopic Constraints

The Organic Refractory Material in the Diffuse Interstellar Medium: Mid‐Infrared Spectroscopic Constraints

Hydrogen peroxide production by ion irradiation of thin water ice films

A 3–5 $\mathsf{\mu}$m VLT spectroscopic survey of embedded young low mass stars II

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