| 321. |
- Persson, Anders, et al.
(författare)
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Improved optogalvanic detection with voltage biased Langmuir probes
- 2014
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 116:24, s. 243301-
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Tidskriftsartikel (refereegranskat)abstract
- Optogalvanic detectors show great potential for infrared spectroscopy, especially in cavity enhanced techniques where they, in contrast to ordinary absorption detectors, can perform intracavity measurements. This enables them to utilize the signal-to-noise ratio improvement gained from the extended effective path length inside an optical cavity, without losing signal strength due to the limited amount of light exiting through the rear mirror. However, if optogalvanic detectors are to become truly competitive, their intrinsic sensitivity and stability has to be improved. This, in turn, requires a better understanding of the mechanisms behind the generation of the optogalvanic signal. The study presented here focuses on an optogalvanic detector based on a miniaturized stripline split-ring resonator plasma source equipped with Langmuir probes for detecting the optogalvanic signal. In particular, the effect of applying a constant bias voltage to one of the probes is investigated, both with respect to the sensitivity and stability, and to the mechanism behind the generation of the signal. Experiments with different bias voltages at different pressures and gas composition have been conducted. In particular, two different gas compositions (pure CO2 and 0.25% CO2 in 99.75% N-2) at six different pressures (100 Pa to 600 Pa) have been studied. It has been shown that probe biasing effectively improves the performance of the detector, by increasing the amplitude of the signal linearly over one order of magnitude, and the stability by about 40% compared with previous studies. Furthermore, it has been shown that relatively straightforward plasma theory can be applied to interpret the mechanism behind the generation of the signal, although additional mechanisms, such as rovibrational excitation from electron-molecule collisions, become apparent in CO2 plasmas with electron energies in the 1-6 eV range. With the achieved performance improvement and the more solid theoretical framework presented here, stripline split-ring resonator optogalvanic detectors can evolve into a compact, inexpensive, and easy-to-operate alternative for future infrared spectrometers. (C) 2014 AIP Publishing LLC.
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| 322. |
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| 323. |
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| 324. |
- Persson, Anders
(författare)
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Intimacy among strangers
- 2001
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Ingår i: Journal of Mundane Behavior. - 1529-3041. ; 2:3, s. 309-316
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Tidskriftsartikel (refereegranskat)abstract
- Mobile telephone calls in public places often entail the revelation of intimate details about the caller's life to strangers. This article reports some results of the authors eavesdropping on mobile phone calls in public places and also takes the first step into analysis of the fascinating mix of visibility and inaccessibility, intimacy and alienation that is the mobile telephone call in a public place. The article discusses how this intimacy among strangers may be understood using Goffman´s concepts of impression management, involvement shields and civil inattention.
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| 325. |
- Persson, Anders
(författare)
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Intimitet bland främlingar. Om mobiltelefonsamtal på offentliga platser
- 2000
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Ingår i: Sociologisk Forskning. - 2002-066X. ; :2/2000, s. 94-98
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Tidskriftsartikel (refereegranskat)abstract
- Mobiltelefonsamtal på offentliga platser kan till det yttre framstå som absurda: en ensam människa som talar, men inte med de andra i närheten. Ofta är man tillräckligt nära för att kunna avlyssna vad som sägs och får ibland höra förbluffande intima detaljer om den talande och om andra. Vad är det som möjliggör denna intimitet bland främlingar? I artikeln utpekas några inslag i en analys, som riktar uppmärksamheten mot den fascinerande blandning av synlighet och otillgänglighet samt av intimitet och främlingskap som mobiltelefonsamtal på offentliga platser utgör.
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| 326. |
- Persson, Anders, et al.
(författare)
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Intracavity optogalvanic spectroscopy: Is there any evidence of a radiocarbon signal?
- 2015
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 361, s. 8-12
-
Tidskriftsartikel (refereegranskat)abstract
- In 2008, the first report of an ultrasensitive method for ro-vibrational spectrometry of radiocarbon dioxide was published. The method, called intracavity optogalvanic spectroscopy (ICOGS), claimed a sensitivity and limit-of-detection comparable to accelerator mass spectroscopy. ICOGS was claimed to utilize the isotope-dependent ro-vibrational absorption lines of carbon dioxide in the infrared spectrum. In order to facilitate unambiguous detection of radiocarbon, the sample was placed inside the cavity of a radiocarbon dioxide laser. This intracavity approach was claimed to increase the sensitivity by seven orders of magnitude compared with traditional optogalvanic methods. However, despite the methodical and thorough efforts of several research groups worldwide, these claims have not been possible to reproduce. Instead, we have previously reported serious deviations from the original results, where we found that ICOGS suffers from considerable problems with the stability and reproducibility of the optogalvanic signal, and that misinterpretations of these uncertainties likely are the explanation for the claimed sensitivity in the first reports. Having identified the stability and reproducibility of the detection as major concerns, we decided to improve the setup by with state-of-the-art plasma source technology. Deploying a custom-made stripline split-ring resonator optogalvanic detector, we have now investigated the applicability of ICOGS to radiocarbon detection even further. Measurements have been made with a wide range of parameters including different gas mixtures at various pressures and wavelengths. We have also conducted measurements with gas flowing through the sample cell to investigate the effect of plasma induced decomposition of the sample. Still, we have seen no indications of a significant radiocarbon signal in a concentration range between 0.29 Modern and 9.7 Modern, i.e., the range of interest to the radiocarbon community. Hence, our conclusions after four years of working in this field, is that ICOGS is not a viable method for radiocarbon detection.
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| 327. |
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| 328. |
- Persson, Anders, 1963-, et al.
(författare)
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Ioncell-F: ionic liquid-based cellulosic textile fibers as an alternative to viscose and Lyocell
- 2016
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Ingår i: Textile research journal. - : Sage Publications. - 0040-5175 .- 1746-7748. ; 86:5, s. 543-552
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Tidskriftsartikel (refereegranskat)abstract
- Ioncell-F, a recently developed process for the production of man-made cellulosic fibers from ionic liquid solutions by dry-jet wet spinning, is presented as an alternative to the viscose and N-methylmorpholine N-oxide (NMMO)-based Lyocell processes. The ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene acetate was identified as excellent cellulose solvent allowing for a rapid dissolution at moderate temperatures and subsequent shaping into continuous filaments. The highly oriented cellulose fibers obtained upon coagulation in cold water exhibited superior tenacity, exceeding that of commercial viscose and NMMO-based Lyocell (Tencel) fibers. The respective staple fibers, which have been converted into two-ply yarn by ring spinning technology, presented very high tenacity. Furthermore, the Ioncell yarn showed very good behavior during the knitting and weaving processes, reflecting the quality of the produced yarn. The successfully knitted and woven garments from the Ioncell yarn demonstrate the suitability of this particular ionic liquid for the production of man-made cellulosic fibers and thus give a promising outlook for the future of the Ioncell-F process.
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| 329. |
- Persson, Anders
(författare)
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Is the Coriolis effect an "optical illusion'?
- 2015
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Ingår i: Quarterly Journal of the Royal Meteorological Society. - : Wiley. - 0035-9009 .- 1477-870X. ; 141:690, s. 1957-1967
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Tidskriftsartikel (refereegranskat)abstract
- The difference between the derivations of the Coriolis effect on a rotating turntable and on the rotating Earth is discussed. In the latter case a real force, the component of the earth's gravitational attraction, non-parallel to the local vertical, plays a central role by balancing the centrifugal force. That a real force is involved leaves open, not only the question on the inertial nature of the inertial oscillations', but also the way we tend to physically conceptualize the terrestrial Coriolis effect.
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| 330. |
- Persson, Anders, 1982-
(författare)
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Israel-Palestinakonfliktens påverkan på antisemitism i Sverige : Världsbilder, delegitimering och tankestrukturer
- 2022
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Ingår i: Statsvetenskaplig Tidskrift. - : Fahlbeckska stiftelsen. - 0039-0747. ; 124:3, s. 775-802
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Tidskriftsartikel (refereegranskat)abstract
- This article analyzes the impact of the Israel-Palestinian conflict on contemporary antisemitism in Sweden. It departs from an analytical framework consisting of three broad components: an Israel-Palestinian-centric worldview, delegitimiza-tion of Israel, Israelis and Zionism, and antisemitic thought structures projected on Israel. The first conclusion of the article is that there has been a clear connection between the Israel-Palestinian conflict and antisemitism in Sweden since the June war of 1967 and even more since the Lebanon war of 1982. Another conclusion is that the Israel-Palestinian centric worldview, which basically argues that the Israeli-Palestinian conflict is more important than other conflicts and key to peace in the wider Middle East, has weakened in Sweden in recent years. A third conclusion is that periods without major outbreaks of violence in the Israel-Palestinian conflict seem to have a calming effect on antisemitism in Sweden, just like escalations in the conflict trigger antisemitism here. We have seen this pattern repeating itself over the past decade and a half with several wars in Gaza and with the most recent escalation between Israel and the Palestinians in May 2021.
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