Water VUV electronic state spectroscopy by synchrotron radiation

Mota, Ronaldo; Parafita, Rui; Giuliani, Alexandre; Hubin‐Franskin, M.‐J.; Lourenço, João P.; García, Gustavo; Hoffmann, Søren Vrønning; Mason, Nigel J.; Ribeiro, Paulo A.; Raposo, Maria; Limão-Vieira, P.

doi:10.1016/j.cplett.2005.09.073

Cited by 194 publications

(213 citation statements)

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“…The effect of flow rate on measured ion intensity with an [24,25] methanol, CH 3 OH (0.5 nm resolution); [26,27] and water, H 2 O (0.075 nm resolution) [28,29] APPI source and LC-MS has been reported previously using a Kr lamp [18], where the signal intensity can be seen to decrease at higher flow rates. Based on Beer's Law, light transmission is I/I 0 ϭ exp(Ϫ nx), which is a function of the wavelength-dependent photoabsorption cross-section, , molecular number density, n, and path length, x.…”

Section: Dependence Of Photoabsorption On Solvent Flowmentioning

confidence: 53%

APPI-MS: Effects of mobile phases and VUV lamps on the detection of PAH compounds

Short¹,

Cai²,

Syage³

2007

J. Am. Soc. Mass Spectrom.

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The technique of atmospheric pressure photoionization (APPI) has several advantages over electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), including efficient ionization of nonpolar or low charge affinity compounds, reduced susceptibility to ion suppression, high sensitivity, and large linear dynamic range. These benefits are greatest at low flow rates (i.e., Յ100 L/min), while at a higher flow, photon absorption and ion-molecule reactions become significant. Under certain circumstances, APPI signal and S/N have been observed to excel at higher flow, which may be due to a nonphotoionzation mechanism. To better understand APPI at higher flow rates, we have selected three lamps (Xe, Kr, and Ar) and four mobile phases typical for reverse-phase, high-pressure liquid chromatography: acetonitrile, methanol, (1:1) acetonitrile:water and (1:1) methanol:water. As test compounds, three polyaromatic hydrocarbons are studied: benzo[a]pyrene, indeno [1,2,3-c, d]pyrene and benz [a]anthracene. We find that solvent photoabsorption cross-section is not the only parameter in explaining relative signal intensity, but that solvent photo-ion chemistry can also play a significant role. Three conclusions from this investigation are: (1) [4,5]. Recent work has focused on the direct comparison of different sources (APPI, APCI, and ESI) with specific target compounds, e.g., polyaromatic hydrocarbons [6,7], hydrophobic peptides [8], pesticides [9,10], as well as fatty acids and lipids [4,5]. In many cases atmospheric pressure photoionization (APPI) [1,7] has demonstrated extended linear dynamic range [11], enhanced sensitivity and thus lower detection limits [6,9,[12][13][14][15], and reduced or no off-line sample cleanups [6,9] in comparison with direct APCI or ESI. Adding a dopant (dopant-assisted, DA) to the mobile phase in many cases can further increase sensitivity [2].A related analytical technique is atmospheric pressure laser ionization (APLI), which has shown excellent sensitivity for certain non-or low-polar compounds [3]. The enhanced sensitivity is a direct result of the high photon flux associated with a laser system, often several orders of magnitude higher than the noncoherent light sources, e.g., lamps used with APPI. The APLI source relies on one-color, two-photon (1 ϩ 1) resonantlyenhanced multiphoton ionization (REMPI), typically using a KrF excimer laser emitting light at 5.0 eV, efficiently ionizing nonpolar molecules. However, APLIis not yet widely used due to the large size, expense, and maintenance associated with the laser system. Furthermore, changing the wavelength of an excimer laser requires the replacement of the gas mixture and often re-tuning of the laser cavity, whereas with an APPI system, the wavelength can be changed by simply switching the lamp.To improve the capabilities of APPI for LC-MS, we have focused on the ion chemistry involved in and following the photoionization process. Although direct, single-photon ionization (SPI) of a compound [M] however, there is litt...

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Section: Dependence Of Photoabsorption On Solvent Flowmentioning

confidence: 53%

APPI-MS: Effects of mobile phases and VUV lamps on the detection of PAH compounds

Short¹,

Cai²,

Syage³

2007

J. Am. Soc. Mass Spectrom.

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“…VUV-absorption cross section as a function of photon wavelength (bottom X-axis) and VUV-photon energy (top X-axis) of pure H 2 O ice deposited at 8 K, black trace. The blue trace is the VUV-absorption cross-section spectrum of gas phase H 2 O taken from Mota et al (2005). The gray area is the measurement error zone.…”

Section: Solid Carbon Monoxidementioning

confidence: 99%

Vacuum-UV spectroscopy of interstellar ice analogs

Cruz-Díaz

Muñoz

Chen

et al. 2014

A&A

110

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Context. The vacuum-UV (VUV) absorption cross sections of most molecular solids present in interstellar ice mantles with the exception of H 2 O, NH 3 , and CO 2 have not been reported yet. Models of ice photoprocessing depend on the VUV absorption cross section of the ice to estimate the penetration depth and radiation dose, and in the past, gas phase cross section values were used as an approximation. Aims. We aim to estimate the VUV absorption cross section of molecular ice components. Methods. Pure ices composed of CO, H 2 O, CH 3 OH, NH 3 , or H 2 S were deposited at 8 K. The column density of the ice samples was measured in situ by infrared spectroscopy in transmittance. VUV spectra of the ice samples were collected in the 120−160 nm (10.33−7.74 eV) range using a commercial microwave-discharged hydrogen flow lamp. Results. We provide VUV absorption cross sections of the reported molecular ices. Our results agree with those previously reported for H 2 O and NH 3 ices. Vacuum-UV absorption cross section of CH 3 OH, CO, and H 2 S in solid phase are reported for the first time. H 2 S presents the highest absorption in the 120−160 nm range. Conclusions. Our method allows fast and readily available VUV spectroscopy of ices without the need to use a synchrotron beamline. We found that the ice absorption cross sections can be very different from the gas-phase values, and therefore, our data will significantly improve models that simulate the VUV photoprocessing and photodesorption of ice mantles. Photodesorption rates of pure ices, expressed in molecules per absorbed photon, can be derived from our data.

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“…In both cases the incoming flux was divided by 4 to account for averaging across the planet, and the contribution of the atmosphere to the planet's cross-sectional area was neglected. To calculate absorption by N 2 , CO 2 , and H 2 O and to estimate the H 2 O photolysis rate, we used N 2 and CO 2 cross-section data from Chan et al (1993b) and Stark et al (1992), H 2 O cross-section data from Chan et al (1993a), Fillion et al (2004), and Mota et al (2005), and H 2 O quantum yields from Huebner et al (1992).…”

Section: Evolution Of Atmospheric Compositionmentioning

confidence: 99%

WATER LOSS FROM TERRESTRIAL PLANETS WITH CO₂-RICH ATMOSPHERES

Wordsworth

Pierrehumbert

2013

ApJ

199

169

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Water photolysis and hydrogen loss from the upper atmospheres of terrestrial planets is of fundamental importance to climate evolution but remains poorly understood in general. Here we present a range of calculations we performed to study the dependence of water loss rates from terrestrial planets on a range of atmospheric and external parameters. We show that CO 2 can only cause significant water loss by increasing surface temperatures over a narrow range of conditions, with cooling of the middle and upper atmosphere acting as a bottleneck on escape in other circumstances. Around G-stars, efficient loss only occurs on planets with intermediate CO 2 atmospheric partial pressures (0.1-1 bar) that receive a net flux close to the critical runaway greenhouse limit. Because G-star total luminosity increases with time but X-ray and ultraviolet/ultravoilet luminosity decreases, this places strong limits on water loss for planets like Earth. In contrast, for a CO 2 -rich early Venus, diffusion limits on water loss are only important if clouds caused strong cooling, implying that scenarios where the planet never had surface liquid water are indeed plausible. Around M-stars, water loss is primarily a function of orbital distance, with planets that absorb less flux than ∼270 W m −2 (global mean) unlikely to lose more than one Earth ocean of H 2 O over their lifetimes unless they lose all their atmospheric N 2 /CO 2 early on. Because of the variability of H 2 O delivery during accretion, our results suggest that many "Earth-like" exoplanets in the habitable zone may have ocean-covered surfaces, stable CO 2 /H 2 O-rich atmospheres, and high mean surface temperatures.

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Water VUV electronic state spectroscopy by synchrotron radiation

Cited by 194 publications

References 23 publications

APPI-MS: Effects of mobile phases and VUV lamps on the detection of PAH compounds

APPI-MS: Effects of mobile phases and VUV lamps on the detection of PAH compounds

Vacuum-UV spectroscopy of interstellar ice analogs

WATER LOSS FROM TERRESTRIAL PLANETS WITH CO₂-RICH ATMOSPHERES

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Water VUV electronic state spectroscopy by synchrotron radiation

Cited by 194 publications

References 23 publications

APPI-MS: Effects of mobile phases and VUV lamps on the detection of PAH compounds

APPI-MS: Effects of mobile phases and VUV lamps on the detection of PAH compounds

Vacuum-UV spectroscopy of interstellar ice analogs

WATER LOSS FROM TERRESTRIAL PLANETS WITH CO2-RICH ATMOSPHERES

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WATER LOSS FROM TERRESTRIAL PLANETS WITH CO₂-RICH ATMOSPHERES