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Kärnä L, Launonen AP, Karjalainen T, Luokkala T, Ponkilainen V, Halonen L, Helminen M, Mattila VM, Reito A. LIMPER trials: immediate mobilisation versus 2-week cast immobilisation after distal radius fracture treated with volar locking plate - a study protocol for a prospective, randomised, controlled trial. BMJ Open 2022; 12:e064440. [PMID: 36368761 PMCID: PMC9660569 DOI: 10.1136/bmjopen-2022-064440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Open reduction and internal fixation with volar locking plate has become the most common fixation method in the treatment of unstable distal radius fracture (DRF). There is, however, no consensus as to whether or for how long a wrist should be immobilised after operative treatment. To date, there have been relatively few studies that have evaluated the effect of immediate postoperative mobilisation on functional outcomes. The aim of postoperative rehabilitation is to obtain a good function and to reduce impairment, recovery time, socioeconomical costs and absence from work. Therefore, there is a need for studies that evaluate the optimal method of postoperative rehabilitation to optimise wrist function and return to work. METHODS AND ANALYSIS This study is a prospective, randomised, controlled trial in which a total of 240 working-age patients who undergo volar plating for DRF will be randomly assigned to either an early mobilisation group or a postoperative 2-week casting group. The aim of the study will be to compare early postoperative outcomes between the study groups. The primary outcome will be patient-rated wrist evaluation at 2 months after operation. A coprimary outcome will be the total length of sick leave. Our follow-up period will be 1 year, and secondary outcomes will include pain, patient satisfaction, perceived ability to work and complications identified at different time points. We expect those patients who undergo immediate mobilisation will have at least as rapid a return to work and function as those patients who undergo postoperative immobilisation, indicating/meaning that there will be no need for postoperative casting. ETHICS AND DISSEMINATION This study will be conducted according to the Standard Protocol Items: Recommendations for Interventional Trials statement. The Ethics committee of Tampere University Hospital has approved the protocol. Ethics committee approval number is R21111, and it is accepted on 7 September 2021. The results of this study will be submitted for publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER NCT05150925.
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Affiliation(s)
- Laura Kärnä
- Tampere University Hospital, Tampere, Finland
| | | | | | - Toni Luokkala
- Central Finland Central Hospital, Jyvaskyla, Finland
| | | | - Lauri Halonen
- South Karelia Central Hospital, Lappeenranta, Finland
| | - Mika Helminen
- Health Sciences, Research Services, Tampere, Finland
- Health Sciences, Tampere University, Tampere, Finland
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2
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Tomberg T, Vuorio N, Hieta T, Jussila M, Hartonen K, Vainio M, Mikkonen T, Toivonen J, Riekkola ML, Halonen L, Metsälä M. Broadband Laser-Based Infrared Detector for Gas Chromatography. Anal Chem 2020; 92:14582-14588. [PMID: 33081464 PMCID: PMC7660589 DOI: 10.1021/acs.analchem.0c02887] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cantilever-enhanced photoacoustic spectroscopy coupled with gas chromatography is used to quantitatively analyze a mixture of alcohols in a quasi-online manner. A full identification and quantification of all analytes are achieved based on their spectral fingerprints using a widely tunable continuous-wave laser as a light source. This can be done even in the case of interfering column/septum bleed or simultaneously eluted peaks. The combination of photoacoustic spectroscopy and gas chromatography offers a viable solution for compact and portable instruments in applications that require straightforward analyses with no consumables.
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Affiliation(s)
- Teemu Tomberg
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Niko Vuorio
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Tuomas Hieta
- Gasera Ltd., Lemminkäisenkatu 59, FI-20520 Turku, Finland
| | - Matti Jussila
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Kari Hartonen
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Markku Vainio
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland.,Photonics Laboratory, Physics Unit, Tampere University, FI-33014 Tampere, Finland
| | - Tommi Mikkonen
- Photonics Laboratory, Physics Unit, Tampere University, FI-33014 Tampere, Finland
| | - Juha Toivonen
- Photonics Laboratory, Physics Unit, Tampere University, FI-33014 Tampere, Finland
| | - Marja-Liisa Riekkola
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Lauri Halonen
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Markus Metsälä
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
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Larnimaa S, Halonen L, Karhu J, Tomberg T, Metsälä M, Genoud G, Hieta T, Bell S, Vainio M. High-resolution analysis of the ν3 band of radiocarbon methane 14CH4. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137488] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Kangas P, Hänninen V, Halonen L. An Ab Initio Molecular Dynamics Study of the Hydrolysis Reaction of Sulfur Trioxide Catalyzed by a Formic Acid or Water Molecule. J Phys Chem A 2020; 124:1922-1928. [PMID: 32068403 DOI: 10.1021/acs.jpca.9b11954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ab initio molecular dynamics (AIMD) calculations have been performed to investigate the role of dynamical and steric effects in formic acid (FA) or H2O-catalyzed gas phase hydrolysis of SO3 to form sulfuric acid. This was done by colliding FA or H2O with the SO3-H2O complex and the water dimer with the SO3 molecule and analyzing the outcomes of 230 AIMD trajectories. Our calculations show that, within simulation times used, sulfuric acid is formed in 5% of FA collisions but is not produced when H2O collides with the SO3-H2O complex or when the water dimer collides with the SO3 molecule. We also find that FA collisions have about 2 times higher probability to form the prereactive complex than H2O collisions. Moreover, our simulations show that the SO3-H2O-FA prereactive complex is more stable in time than the SO3-H2O-H2O prereactive complex. These findings indicate that the FA-catalyzed mechanism is favored over the H2O one when looking from the steric and dynamic effect point of view. Additionally, AIMD simulations starting from the optimized structure of the SO3-H2O-FA prereactive complex have been computed to qualitatively estimate the rate of the sulfuric acid formation. Collisional energy has been observed to promote sulfuric acid formation more effectively than thermal excitation.
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Affiliation(s)
- Pinja Kangas
- Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 Helsinki, Finland
| | - Vesa Hänninen
- Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 Helsinki, Finland
| | - Lauri Halonen
- Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 Helsinki, Finland
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Daub CD, Riccardi E, Hänninen V, Halonen L. Path sampling for atmospheric reactions: formic acid catalysed conversion of SO3 + H2O to H2SO4. PeerJ Physical Chemistry 2020. [DOI: 10.7717/peerj-pchem.7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Atmospheric reactions, hitherto studied computationally mainly with static computations in conjunction with transition state theories, can be further described via path sampling calculations. Here we report on an exploratory study of the formic acid catalysed hydrolysis of SO3 to produce H2SO4. We demonstrate that precise measurements of rate coefficients can be obtained in principle for such reactions with an acceptable expenditure of computational resources, and that new insights into the reaction can be obtained by the analysis of the path space explored via path sampling techniques.
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Affiliation(s)
| | - Enrico Riccardi
- Department of Chemistry, Norwegian University of Science and Technology, Trondheim, Norway
| | - Vesa Hänninen
- Department of Chemistry, University of Helsinki, Helsinki, Finland
| | - Lauri Halonen
- Department of Chemistry, University of Helsinki, Helsinki, Finland
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Roslund K, Lehto M, Pussinen P, Groop PH, Halonen L, Metsälä M. On-line profiling of volatile compounds produced in vitro by pathogenic oral bacteria. J Breath Res 2019; 14:016010. [PMID: 31698353 DOI: 10.1088/1752-7163/ab5559] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Infections by oral pathogens are one of the most common health problems worldwide. Due to the intimate connection between exhaled breath and the oral cavity, breath analysis could potentially be used to diagnose these infections. However, little is known about the volatile emissions of important oral pathogens that are connected with gingivitis and periodontitis. In this study, we have performed in vitro headspace measurements on four important oral pathogens (P. gingivalis, T. forsythia, P. intermedia and P. nigrescens) using proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS). Some of the most abundant compounds produced by the bacteria include hydrogen sulphide, methanethiol, acetone, dimethylsulphide, isoprene, cyclopentanone and indole as tentatively assigned from the mass spectra. Several other abundant mass signals were recorded but the assignment of these is less certain. Some of the bacterial species can be separated from each other by the emitted volatile fingerprints. The results of this study can be used in potential development of a diagnostic breath test for oral infections. In addition, as several of the measured compounds are known to be toxic, the results point to an intriguing possibility of studying the connection between the bacterial virulence and the emitted volatile compounds.
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Affiliation(s)
- Kajsa Roslund
- Department of Chemistry, University of Helsinki, Helsinki, Finland
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7
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Daub CD, Halonen L. Ab Initio Molecular Dynamics Simulations of the Influence of Lithium Bromide Salt on the Deprotonation of Formic Acid in Aqueous Solution. J Phys Chem B 2019; 123:6823-6829. [PMID: 31310529 PMCID: PMC6750841 DOI: 10.1021/acs.jpcb.9b04618] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The deprotonation of formic acid is investigated using metadynamics in tandem with Born-Oppenheimer molecular dynamics simulations. We compare our findings for formic acid in pure water with previous studies before examining formic acid in aqueous solutions of lithium bromide. We carefully consider different definitions for the collective variable(s) used to drive the metadynamics, emphasizing that the variables used must include all of the possible reactive atoms in the system, in this case carboxylate oxygens and water hydrogens. This ensures that all the various possible proton exchange events can be accommodated and the collective variable(s) can distinguish the protonated and deprotonated states, even over rather long ab initio simulation runs (ca. 200-300 ps). Our findings show that the formic acid deprotonation barrier and the free energy of the deprotonated state are higher in concentrated lithium bromide, in agreement with the available experimental data for acids in salt solution. We show that the presence of Br- in proximity to the formic acid hydroxyl group effectively inhibits deprotonation. Our study extends previous work on acid deprotonation in pure water and at air-water interfaces to more complex multicomponent systems of importance in atmospheric and marine chemistry.
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Affiliation(s)
- Christopher D Daub
- Department of Chemistry , University of Helsinki , P.O. Box 55, Helsinki FIN-00014 , Finland
| | - Lauri Halonen
- Department of Chemistry , University of Helsinki , P.O. Box 55, Helsinki FIN-00014 , Finland
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Abstract
We have improved the sensitivity of a state-of-the-art cantilever-enhanced photo-acoustic trace gas sensor by combining it with an optical power build-up cavity. The build-up cavity enhances the photo-acoustic signal by a factor of ∼100, resulting in an exceptionally good normalised noise equivalent absorption (NNEA) value of 1.75 × 10-12 W cm-1 Hz-1/2. We demonstrate the sensor platform in the 1530 nm wavelength range with a simple distributed feedback diode laser, achieving 75 ppt sensitivity for C2H2 with a 10 s integration time.
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Affiliation(s)
- Teemu Tomberg
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
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9
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Karhu J, Tomberg T, Senna Vieira F, Genoud G, Hänninen V, Vainio M, Metsälä M, Hieta T, Bell S, Halonen L. Broadband photoacoustic spectroscopy of CH 414 with a high-power mid-infrared optical frequency comb. Opt Lett 2019; 44:1142-1145. [PMID: 30821733 DOI: 10.1364/ol.44.001142] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 01/22/2019] [Indexed: 06/09/2023]
Abstract
We report a photoacoustic spectroscopy setup with a high-power mid-infrared frequency comb as the light source. The setup is used in broadband spectroscopy of radiocarbon methane. Owing to the high sensitivity of a cantilever-enhanced photoacoustic cell and the high-power light source, we can reach a detection limit below 100 ppb in a broadband measurement with a sample volume of only a few milliliters. The first infrared spectrum of CH414 is reported and given a preliminary assignment. The results lay a foundation for the development of optical detection systems for radiocarbon methane.
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Daub CD, Hänninen V, Halonen L. Ab Initio Molecular Dynamics Simulations of the Influence of Lithium Bromide on the Structure of the Aqueous Solution-Air Interface. J Phys Chem B 2019; 123:729-737. [PMID: 30605330 PMCID: PMC6727360 DOI: 10.1021/acs.jpcb.8b10552] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
We
present the results of ab initio molecular dynamics simulations
of the solution–air interface of aqueous lithium bromide (LiBr).
We find that, in agreement with the experimental data and previous
simulation results with empirical polarizable force field models,
Br– anions prefer to accumulate just below the first
molecular water layer near the interface, whereas Li+ cations
remain deeply buried several molecular layers from the interface,
even at very high concentration. The separation of ions has a profound
effect on the average orientation of water molecules in the vicinity
of the interface. We also find that the hydration number of Li+ cations in the center of the slab Nc,Li+–H2O ≈ 4.7 ±
0.3, regardless of the salt concentration. This estimate is consistent
with the recent experimental neutron scattering data, confirming that
results from nonpolarizable empirical models, which consistently predict
tetrahedral coordination of Li+ to four solvent molecules,
are incorrect. Consequently, disruption of the hydrogen bond network
caused by Li+ may be overestimated in nonpolarizable empirical
models. Overall, our results suggest that empirical models, in particular
nonpolarizable models, may not capture all of the properties of the
solution–air interface necessary to fully understand the interfacial
chemistry.
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Affiliation(s)
- Christopher D Daub
- Department of Chemistry , University of Helsinki , P.O. Box 55, Helsinki 00014 , Finland
| | - Vesa Hänninen
- Department of Chemistry , University of Helsinki , P.O. Box 55, Helsinki 00014 , Finland
| | - Lauri Halonen
- Department of Chemistry , University of Helsinki , P.O. Box 55, Helsinki 00014 , Finland
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Karhu J, Lehmann K, Vainio M, Metsälä M, Halonen L. Step-modulated decay cavity ring-down detection for double resonance spectroscopy. Opt Express 2018; 26:29086-29098. [PMID: 30470075 DOI: 10.1364/oe.26.029086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 09/22/2018] [Indexed: 06/09/2023]
Abstract
A method of measuring double resonant two-photon signal and background from a single cavity ring-down decay is introduced. This is achieved by modulating the double resonance loss via one of the light sources exciting the transition. The noise performance of the method is characterized theoretically and experimentally. The addition of a new parameter to the fitting function introduces a minor noise increase due to parameter correlation. However, the concurrent recording of the background can extend the stable measurement time. Alternatively, the method allows a faster measurement speed, while still recording the background, which is often advantageous in double resonance measurements. Finally, the method is insensitive to changes in the cavity decay rate at short timescales and can lead to improved performance if they have significant contribution to the final noise level compared to the detector noise.
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Hänninen V, Murdachaew G, Nathanson GM, Gerber RB, Halonen L. Ab initio molecular dynamics studies of formic acid dimer colliding with liquid water. Phys Chem Chem Phys 2018; 20:23717-23725. [PMID: 30191926 DOI: 10.1039/c8cp03857k] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ab initio molecular dynamics simulations of formic acid (FA) dimer colliding with liquid water at 300 K have been performed using density functional theory. The two energetically lowest FA dimer isomers were collided with a water slab at thermal and high kinetic energies up to 68kBT. Our simulations agree with recent experimental observations of nearly a complete uptake of gas-phase FA dimer: the calculated average kinetic energy of the dimers immediately after collision is 5 ± 4% of the incoming kinetic energy, which compares well with the experimental value of 10%. Simulations support the experimental observation of no delayed desorption of FA dimers following initial adsorption. Our analysis shows that the FA dimer forms hydrogen bonds with surface water molecules, where the hydrogen bond order depends on the dimer structure, such that the most stable isomer possesses fewer FA-water hydrogen bonds than the higher energy isomer. Nevertheless, even the most stable isomer can attach to the surface through one hydrogen bond despite its reduced hydrophilicity. Our simulations further show that the probability of FA dimer dissociation is increased by high collision energies, the dimer undergoes isomerization from the higher energy to the lowest energy isomer, and concerted double-proton transfer occurs between the FA monomers. Interestingly, proton transfer appears to be driven by the release of energy arising from such isomerization, which stimulates those internal vibrational degrees of freedom that overcome the barrier of a proton transfer.
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Affiliation(s)
- Vesa Hänninen
- Department of Chemistry, University of Helsinki, P. O. Box 55 (A.I. Virtasen aukio 1), FI-00014, Finland.
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Lassmann-Klee PG, Lindholm T, Metsälä M, Halonen L, Sovijärvi ARA, Piirilä P. Reduction of F ENO by tap water and carbonated water mouthwashes: magnitude and time course. Scand J Clin Lab Invest 2018; 78:153-156. [PMID: 29304558 DOI: 10.1080/00365513.2017.1419574] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Fractional exhaled nitric oxide (FENO) assesses eosinophilic inflammation of the airways, but FENO values are also influenced by oral nitric oxide (NO). The aim of this pilot study was to measure FENO and compare the effect of two different mouthwashes on FENO and analyse the duration of the effect. FENO was measured in 12 randomized volunteers (healthy or asthmatic subjects) with a NIOX VERO® analyser at an expiratory flow rate of 50 mL/s. After a baseline measurement, a mouthwash was performed either with tap water or carbonated water and was measured during 20 min in 2 min intervals. The procedure was repeated with the other mouthwash. We found that both mouthwashes reduced FENO immediately at the beginning compared to the baseline (p < .001). The carbonated water mouthwash effect lasted 12 min (p ranging from <0.001 to <0.05). The tap water mouthwash reduced FENO statistically significantly only for 2 min compared with the baseline. We conclude that a single carbonated water mouthwash can significantly reduce the oropharyngeal NO contribution during a 12 min time interval.
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Affiliation(s)
- Paul Guenther Lassmann-Klee
- a Unit of Clinical Physiology , Helsinki University Central Hospital, University of Helsinki , Helsinki , Finland
| | - Tuula Lindholm
- b Laboratory of Clinical Physiology , Finnish Institute of Occupational Health , Helsinki , Finland
| | - Markus Metsälä
- c Department of Chemistry , University of Helsinki , Helsinki , Finland
| | - Lauri Halonen
- c Department of Chemistry , University of Helsinki , Helsinki , Finland
| | - Anssi Raimo Antero Sovijärvi
- a Unit of Clinical Physiology , Helsinki University Central Hospital, University of Helsinki , Helsinki , Finland
| | - Päivi Piirilä
- a Unit of Clinical Physiology , Helsinki University Central Hospital, University of Helsinki , Helsinki , Finland
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Vainio M, Halonen L. Stabilization of femtosecond optical parametric oscillators for infrared frequency comb generation. Opt Lett 2017; 42:2722-2725. [PMID: 28708153 DOI: 10.1364/ol.42.002722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 06/12/2017] [Indexed: 06/07/2023]
Abstract
A synchronously pumped optical parametric oscillator (SP-OPO) is one of the most common techniques to generate femtosecond frequency combs in the mid-infrared region. Stable long-term operation of an SP-OPO requires active locking of the OPO resonator round-trip time to the pump pulse interval. A simple modulation-free locking method based on stabilization of narrow-band frequency-doubled power of the SP-OPO output comb is demonstrated in this Letter. The method relies on the strong dependency of frequency-doubled power on spectral shape of the comb, leading to better stability of the comb envelope spectrum than the commonly used dither-and-lock method.
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Abstract
We report a setup for high-resolution two-photon spectroscopy using a mid-infrared continuous wave optical parametric oscillator (CW-OPO) and a near-infrared diode laser as the excitation sources, both of which are locked to fully stabilized optical frequency combs. The diode laser is directly locked to a commercial near-infrared optical frequency comb using an optical phase-locked loop. The near-infrared frequency comb is also used to synchronously pump a degenerate femtosecond optical parametric oscillator to produce a fully stabilized mid-infrared frequency comb. The beat frequency between the mid-infrared comb and the CW-OPO is then stabilized through frequency locking. We used the setup to measure a double resonant two-photon transition to a symmetric vibrational state of acetylene with a sub-Doppler resolution and high signal-to-noise ratio.
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Partanen L, Hänninen V, Halonen L. Effects of Global and Local Anharmonicities on the Thermodynamic Properties of Sulfuric Acid Monohydrate. J Chem Theory Comput 2016; 12:5511-5524. [PMID: 27662456 DOI: 10.1021/acs.jctc.6b00683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We use state-of-the-art electronic structure calculation methods and large basis sets to obtain reliable values for the thermodynamic properties of sulfuric acid monohydrate and study the effects of vibrational anharmonicity on these properties. We distinguish between two forms of vibrational anharmonicity: local anharmonicity, which refers to the anharmonicity of the vibrational modes of a given cluster conformer, and global anharmonicity, which originates from accounting for the presence of different conformers in the first place. In our most accurate approach, we solve the nuclear Schrödinger equation variationally for the intermolecular large-amplitude motions, thus quantum-mechanically accounting for the presence of higher-energy conformers for both reactants and products, while using the standard vibrational perturbational approach for the other vibrational modes. This results in a value of -11.0 kJ/mol for the reaction Gibbs free energy at 298.15 K. When standard vibrational perturbational approaches are employed, the effects of local anharmonicity depend heavily on the choice of the electronic structure calculation basis set. In fact, better results can often be achieved by combining a simple harmonic treatment for the vibrational partition function with a statistical mechanical accounting of global anharmonicity. Thus, we recommend that future studies that intend to include anharmonicity start by accounting for the presence of higher-energy conformers and only then consider whether local anharmonicity calculations are feasible and necessary.
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Affiliation(s)
- Lauri Partanen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, A.I. Virtasen aukio 1, FIN-00014 Helsinki, Finland
| | - Vesa Hänninen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, A.I. Virtasen aukio 1, FIN-00014 Helsinki, Finland
| | - Lauri Halonen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, A.I. Virtasen aukio 1, FIN-00014 Helsinki, Finland
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Chen W, Laiho S, Vaittinen O, Halonen L, Ortiz F, Forsblom C, Groop PH, Lehto M, Metsälä M. Biochemical pathways of breath ammonia (NH
3
) generation in patients with end-stage renal disease undergoing hemodialysis. J Breath Res 2016; 10:036011. [DOI: 10.1088/1752-7155/10/3/036011] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Karhu J, Nauta J, Vainio M, Metsälä M, Hoekstra S, Halonen L. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy. J Chem Phys 2016; 144:244201. [DOI: 10.1063/1.4954159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- J. Karhu
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - J. Nauta
- Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands
| | - M. Vainio
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
- VTT Technical Research Centre of Finland Ltd., Centre of Metrology MIKES, P.O. Box 1000, Espoo FI-02044 VTT, Finland
| | - M. Metsälä
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - S. Hoekstra
- Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands
| | - L. Halonen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
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Chen W, Roslund K, Fogarty CL, Pussinen PJ, Halonen L, Groop PH, Metsälä M, Lehto M. Detection of hydrogen cyanide from oral anaerobes by cavity ring down spectroscopy. Sci Rep 2016; 6:22577. [PMID: 26940198 PMCID: PMC4778072 DOI: 10.1038/srep22577] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/17/2016] [Indexed: 02/07/2023] Open
Abstract
Hydrogen cyanide (HCN) has been recognized as a potential biomarker for non-invasive diagnosis of Pseudomonas aeruginosa infection in the lung. However, the oral cavity is a dominant production site for exhaled HCN and this contribution can mask the HCN generated in the lung. It is thus important to understand the sources of HCN production in the oral cavity. By screening of oral anaerobes for HCN production, we observed that the genus of Porphyromonas, Prevotella and Fusobacterium generated low levels of HCN in vitro. This is the first study to show that oral anaerobes are capable of producing HCN in vitro. Further investigations were conducted on the species of P. gingivalis and we successfully detected HCN production (0.9-10.9 ppb) in the headspace of three P. gingivalis reference strains (ATCC 33277, W50 and OMG 434) and one clinical isolate. From P. gingivalis ATCC 33277 and W50, a strong correlation between HCN and CO2 concentrations (rs = 0.89, p < 0.001) was observed, indicating that the HCN production of P. gingivalis might be connected with the bacterial metabolic activity. These results indicate that our setup could be widely applied to the screening of in vitro HCN production by both aerobic and anaerobic bacteria.
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Affiliation(s)
- Wen Chen
- Department of Chemistry, University of Helsinki, Finland
| | - Kajsa Roslund
- Department of Chemistry, University of Helsinki, Finland.,Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland.,Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.,Research Programs Unit, Diabetes and Obesity, University of Helsinki, Helsinki, Finland
| | - Christopher L Fogarty
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland.,Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.,Research Programs Unit, Diabetes and Obesity, University of Helsinki, Helsinki, Finland
| | - Pirkko J Pussinen
- Oral and Maxillofacial Diseases, University of Helsinki and Helsinki University Hospital, Finland
| | - Lauri Halonen
- Department of Chemistry, University of Helsinki, Finland
| | - Per-Henrik Groop
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland.,Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.,Research Programs Unit, Diabetes and Obesity, University of Helsinki, Helsinki, Finland
| | - Markus Metsälä
- Department of Chemistry, University of Helsinki, Finland
| | - Markku Lehto
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland.,Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.,Research Programs Unit, Diabetes and Obesity, University of Helsinki, Helsinki, Finland
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20
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Murdachaew G, Nathanson GM, Benny Gerber R, Halonen L. Deprotonation of formic acid in collisions with a liquid water surface studied by molecular dynamics and metadynamics simulations. Phys Chem Chem Phys 2016; 18:29756-29770. [DOI: 10.1039/c6cp06071d] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Formic acid has a lower barrier to deprotonation at the air–water interface than in bulk liquid water.
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Affiliation(s)
- Garold Murdachaew
- Laboratory of Physical Chemistry
- Department of Chemistry
- FI-00014 University of Helsinki
- Finland
| | | | - R. Benny Gerber
- Laboratory of Physical Chemistry
- Department of Chemistry
- FI-00014 University of Helsinki
- Finland
- Institute of Chemistry and the Fritz Haber Research Center
| | - Lauri Halonen
- Laboratory of Physical Chemistry
- Department of Chemistry
- FI-00014 University of Helsinki
- Finland
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21
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Abstract
Review of mid-infrared optical parametric oscillators and frequency combs for high-resolution spectroscopy, including applications in trace gas detection and fundamental research.
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Affiliation(s)
- M. Vainio
- Laboratory of Physical Chemistry
- Department of Chemistry
- University of Helsinki
- Finland
- VTT Technical Research Centre of Finland Ltd
| | - L. Halonen
- Laboratory of Physical Chemistry
- Department of Chemistry
- University of Helsinki
- Finland
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22
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Partanen L, Murdachaew G, Gerber RB, Halonen L. Temperature and collision energy effects on dissociation of hydrochloric acid on water surfaces. Phys Chem Chem Phys 2016; 18:13432-42. [DOI: 10.1039/c6cp00597g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Hatz R, Korpinen M, Hänninen V, Halonen L. Generalized Intermolecular Interaction Tensor Applied to Long-Range Interactions in Hydrogen and Coinage Metal (Cu, Ag, and Au) Clusters. J Phys Chem A 2015; 119:11729-36. [PMID: 26501212 DOI: 10.1021/acs.jpca.5b09080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a novel formulation for the intermolecular interaction tensor, which is used to describe the long-range electrostatic, induction, and dispersion interactions. Our formulation is based on concepts drawn from combinatorial analysis and Clifford calculus and enables us to present the interaction tensor in a form that is simple to use and suitable for both numerical and symbolic analyses. We apply the derived formulas to calculate the long-range interaction coefficients in hydrogen and coinage metal (Cu, Ag, and Au) clusters. The electronic structure calculations are performed at the CCSD(T) level, with triple-ζ and quadruple-ζ basis sets. The multipole moments and dispersion coefficients are obtained as fits to the derived interaction formulas. The most important interaction parameters are obtained accurately and are in good agreement with other results.
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Affiliation(s)
- Richard Hatz
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland
| | - Markus Korpinen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland
| | - Vesa Hänninen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland
| | - Lauri Halonen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland
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24
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Mackeprang K, Hänninen V, Halonen L, Kjaergaard HG. The effect of large amplitude motions on the vibrational intensities in hydrogen bonded complexes. J Chem Phys 2015; 142:094304. [DOI: 10.1063/1.4913737] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Peltola J, Vainio M, Fordell T, Hieta T, Merimaa M, Halonen L. Frequency-comb-referenced mid-infrared source for high-precision spectroscopy. Opt Express 2014; 22:32429-32439. [PMID: 25607205 DOI: 10.1364/oe.22.032429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report on a tunable continuous-wave mid-infrared optical parametric oscillator (OPO), which is locked to a fully stabilized near-infrared optical frequency comb using a frequency doubling scheme. The OPO is used for 40 GHz mode-hop-free, frequency-comb-locked scans in the wavelength region between 2.7 and 3.4 μm. We demonstrate the applicability of the method to high-precision cavity-ring-down spectroscopy of nitrous oxide (N2O) and water (H2O) at 2.85 µm and of methane (CH4) at 3.2 μm.
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26
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Abstract
Dispersion interactions between group 12 (Zn, Cd, Hg) metal clusters are studied at the CCSD(T) level with triple-ζ basis sets. We use atomic orientation dependent C6 dispersion coefficients derived from simple model systems to calculate the intermolecular dispersion energy between larger metal clusters. By using an atomic pair-potential model, we are able to obtain highly accurate results comparable to the CCSD(T) level of theory. For all the systems studied, our method results in a robust description of the dispersion energy at long distances, and it is able to outperform the examined dispersion corrected DFT calculations.
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Affiliation(s)
- Richard Hatz
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 Helsinki, Finland
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27
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Abstract
It is known that the oral cavity is a production site for mouth-exhaled NH3. However, the mechanism of NH3 production in the oral cavity has been unclear. Since bacterial urease in the oral cavity has been found to produce ammonia from oral fluid urea, we hypothesize that oral fluid urea is the origin of mouth-exhaled NH3. Our results show that under certain conditions a strong correlation exists between oral fluid urea and oral fluid ammonia (NH4(+)+NH3) (rs = 0.77, p < 0.001). We also observe a strong correlation between oral fluid NH3 and mouth-exhaled NH3 (rs = 0.81, p < 0.001). We conclude that three main factors affect the mouth-exhaled NH3 concentration: urea concentration, urease activity and oral fluid pH. Bacterial urease catalyses the hydrolysis of oral fluid urea to ammonia (NH4(+)+NH3). Oral fluid ammonia (NH4(+)+NH3) and pH determine the concentration of oral fluid NH3, which evaporates from oral fluid into gas phase and turns to mouth-exhaled NH3.
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Affiliation(s)
- W Chen
- Laboratory of Physical Chemistry, Department of Chemistry, PO Box 55 (A. I. Virtasen aukio 1), FI-00014 University of Helsinki, Finland
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28
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Affiliation(s)
- Richard Hatz
- Laboratory
of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55
(A.I. Virtasen aukio 1), FIN-00014 Helsinki, Finland
| | - Vesa Hänninen
- Laboratory
of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55
(A.I. Virtasen aukio 1), FIN-00014 Helsinki, Finland
| | - Lauri Halonen
- Laboratory
of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55
(A.I. Virtasen aukio 1), FIN-00014 Helsinki, Finland
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29
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Affiliation(s)
- S. Riikonen
- Laboratory
of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland
| | - P. Parkkinen
- Laboratory
of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland
| | - L. Halonen
- Laboratory
of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland
| | - R. B. Gerber
- Laboratory
of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland
- Institute
of Chemistry and the Fritz Haber Research Center, The Hebrew University, Jerusalem 91904 Israel
- Department
of Chemistry, University of California Irvine, Irvine, California 92697, United States
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30
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31
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Mackeprang K, Kjaergaard HG, Salmi T, Hänninen V, Halonen L. The effect of large amplitude motions on the transition frequency redshift in hydrogen bonded complexes: A physical picture. J Chem Phys 2014; 140:184309. [DOI: 10.1063/1.4873420] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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32
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Ulvila V, Phillips CR, Halonen L, Vainio M. High-power mid-infrared frequency comb from a continuous-wave-pumped bulk optical parametric oscillator. Opt Express 2014; 22:10535-10543. [PMID: 24921755 DOI: 10.1364/oe.22.010535] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate that it is possible to obtain a mid-infrared optical frequency comb (OFC) experimentally by using a continuous-wave-pumped optical parametric oscillator (OPO). The comb is generated without any active modulation. It is based on cascading quadratic nonlinearities that arise from intra-cavity phase mismatched second harmonic generation of the signal wave that resonates in the OPO. The generated OFC is transferred from the signal wavelength (near-infrared) to the idler wavelength (mid-infrared) by intracavity difference frequency generation between the OPO pump wave and the signal comb. We have produced a mid-infrared frequency comb which is tunable from 3.0 to 3.4 µm with an average output power of up to 3.1 W.
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33
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Parkkinen P, Riikonen S, Halonen L. Configurational Entropy in Ice Nanosystems: Tools for Structure Generation and Screening. J Chem Theory Comput 2014; 10:1256-64. [PMID: 26580194 DOI: 10.1021/ct400931p] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recently, a number of experimental and theoretical studies of low-temperature ice and water in nanoscale systems have emerged. Any theoretical study trying to model such systems will encounter the proton-disorder problem, i.e., there exist many configurations differing by water-molecule rotations for a fixed oxygen atom structure. An extensive search within the allowed proton-disorder space should always be perfomed to ensure a reasonable low-energy isomer and to address the effect of proton-configurational entropy that may affect experimental observables. In the present work, an efficient general-purpose program for finite, semiperiodic, and periodic systems of hydrogen-bonded molecules is presented, which can be used in searching and enumerating the proton-configurational ensemble. Benchmarking tests are performed for ice nanotubes and finite slabs. Finally, the program is applied to experimentally appropriate ice nanosystems. A boron nitride film supported ice nanodot is studied in detail. Using a systematic generation of its proton-configurational ensemble, we find an isomer that is ∼1 eV lower in total energy than one previously studied. The present isomer features a considerable dipole moment and implies that ice nanodots are inherently ferroelectric parallel to the surface. We conclude by demonstrating how the so-called hydrogen-bond connectivity parameters can be used to screen low-energy isomers.
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Affiliation(s)
- P Parkkinen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, FI-00014, Helsinki, Finland
| | - S Riikonen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, FI-00014, Helsinki, Finland
| | - L Halonen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki , P.O. Box 55, FI-00014, Helsinki, Finland
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34
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Murdachaew G, Gaigeot MP, Halonen L, Gerber RB. First and second deprotonation of H2SO4on wet hydroxylated (0001) α-quartz. Phys Chem Chem Phys 2014; 16:22287-98. [DOI: 10.1039/c4cp02752c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We present anab initiomolecular dynamics study of deprotonation of sulfuric acid on wet quartz, a topic of atmospheric interest.
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Affiliation(s)
- Garold Murdachaew
- Laboratory of Physical Chemistry
- Department of Chemistry
- University of Helsinki
- FI-00014 Helsinki, Finland
| | - Marie-Pierre Gaigeot
- LAMBE
- CNRS UMR 8587
- Université d'Evry val d'Essonne
- Boulevard François Mitterrand
- 91025 Evry, France
| | - Lauri Halonen
- Laboratory of Physical Chemistry
- Department of Chemistry
- University of Helsinki
- FI-00014 Helsinki, Finland
| | - R. Benny Gerber
- Laboratory of Physical Chemistry
- Department of Chemistry
- University of Helsinki
- FI-00014 Helsinki, Finland
- Institute of Chemistry and the Fritz Haber Research Center
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35
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Ulvila V, Phillips CR, Halonen L, Vainio M. Frequency comb generation by a continuous-wave-pumped optical parametric oscillator based on cascading quadratic nonlinearities. Opt Lett 2013; 38:4281-4284. [PMID: 24177073 DOI: 10.1364/ol.38.004281] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report optical frequency comb generation by a continuous-wave pumped optical parametric oscillator (OPO) without any active modulation. The OPO is configured as singly resonant with an additional nonlinear crystal (periodically poled MgO:LiNbO3) placed inside the OPO for phase mismatched second harmonic generation (SHG) of the resonating signal beam. The phase mismatched SHG causes cascading χ(2) nonlinearities, which can substantially increase the effective χ(3) nonlinearity in MgO:LiNbO3, leading to spectral broadening of the OPO signal beam via self-phase modulation. The OPO generates a stable 4 THz wide (-30 dB) frequency comb centered at 1.56 μm.
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36
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37
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Siltanen M, Metsälä M, Vainio M, Halonen L. Experimental observation and analysis of the 3ν1(Σg) stretching vibrational state of acetylene using continuous-wave infrared stimulated emission. J Chem Phys 2013; 139:054201. [DOI: 10.1063/1.4816524] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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38
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Affiliation(s)
- P. Parkkinen
- Laboratory
of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki,
Finland
| | - S. Riikonen
- Laboratory
of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki,
Finland
| | - L. Halonen
- Laboratory
of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki,
Finland
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39
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Riikonen S, Parkkinen P, Halonen L, Gerber RB. Ionization of Nitric Acid on Crystalline Ice: The Role of Defects and Collective Proton Movement. J Phys Chem Lett 2013; 4:1850-1855. [PMID: 26283120 DOI: 10.1021/jz400531q] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ionization of nitric acid (HNO3) on a model ice surface is studied using ab initio molecular dynamics at temperatures of 200 and 40 K with a surface slab model that consists of the ideal ice basal plane with locally optimized and annealed defects. Pico- and subpicosecond ionization of nitric acid can be achieved in the defect sites. Key features of the rapid ionization are (a) the efficient solvation of the polyatomic nitrate anion, by stealing hydrogen bonds from the weakened hydrogen bonds at defect sites, (b) formation of contact ion pairs to stable "presolvated" molecular species that are present at the defects,
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Affiliation(s)
- S Riikonen
- †Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland
| | - P Parkkinen
- †Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland
| | - L Halonen
- †Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland
| | - R B Gerber
- †Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland
- ‡Institute of Chemistry and the Fritz Haber Research Center, The Hebrew University, Jerusalem 91904 Israel
- §Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
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40
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Peltola J, Vainio M, Hieta T, Uotila J, Sinisalo S, Metsälä M, Siltanen M, Halonen L. High sensitivity trace gas detection by cantilever-enhanced photoacoustic spectroscopy using a mid-infrared continuous-wave optical parametric oscillator. Opt Express 2013; 21:10240-10250. [PMID: 23609733 DOI: 10.1364/oe.21.010240] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Highly sensitive cantilever-enhanced photoacoustic detection of hydrogen cyanide and methane in the mid-infrared region is demonstrated. A mid-infrared continuous-wave frequency tunable optical parametric oscillator was used as a light source in the experimental setup. Noise equivalent detection limits of 190 ppt (1 s) and 65 ppt (30 s) were achieved for HCN and CH(4), respectively. The normalized noise equivalent absorption coefficient is 1.8 × 10(-9) W cm(-1) Hz(-1/2).
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Affiliation(s)
- Jari Peltola
- Laboratory of Physical Chemistry, Department of Chemistry, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland
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41
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42
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Abstract
Ammonia concentrations in exhaled breath (eNH3) and skin gas of 20 healthy subjects were measured on-line with a commercial cavity ring-down spectrometer and compared to saliva pH and plasma ammonium ion (NH(+)4), urea and creatinine concentrations. Special attention was given to mouth, nose and skin sampling procedures and the accurate quantification of ammonia in humid gas samples. The obtained median concentrations were 688 parts per billion by volume (ppbv) for mouth-eNH3, 34 ppbv for nose-eNH3, and 21 ppbv for both mouth- and nose-eNH3 after an acidic mouth wash (MW). The median ammonia emission rate from the lower forearm was 0.3 ng cm(-2) min(-1). Statistically significant (p < 0.05) correlations between the breath, skin and plasma ammonia/ammonium concentrations were not found. However, mouth-eNH3 strongly (p < 0.001) correlated with saliva pH. This dependence was also observed in detailed measurements of the diurnal variation and the response of eNH3 to the acidic MW. It is concluded that eNH3 as such does not reflect plasma but saliva and airway mucus NH(+)4 concentrations and is affected by saliva and airway mucus pH. After normalization with saliva pH using the Henderson-Hasselbalch equation, mouth-eNH3 correlated with plasma NH(+)4, which points to saliva and plasma NH(+)4 being linked via hydrolysis of salivary urea.
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Affiliation(s)
- F M Schmidt
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, Finland.
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43
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Hatz R, Korpinen M, Hänninen V, Halonen L. Characterization of the Dispersion Interactions and an ab Initio Study of van der Waals Potential Energy Parameters for Coinage Metal Clusters. J Phys Chem A 2012; 116:11685-93. [DOI: 10.1021/jp307448n] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Richard Hatz
- Laboratory of Physical
Chemistry, Department
of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki,
Finland
| | - Markus Korpinen
- Laboratory of Physical
Chemistry, Department
of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki,
Finland
| | - Vesa Hänninen
- Laboratory of Physical
Chemistry, Department
of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki,
Finland
| | - Lauri Halonen
- Laboratory of Physical
Chemistry, Department
of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki,
Finland
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44
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Vainio M, Merimaa M, Halonen L, Vodopyanov K. Degenerate 1 GHz repetition rate femtosecond optical parametric oscillator. Opt Lett 2012; 37:4561-4563. [PMID: 23114363 DOI: 10.1364/ol.37.004561] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report a degenerate femtosecond optical parametric oscillator (OPO) that is synchronously pumped by a mode-locked Ti:sapphire laser at 1 GHz repetition rate. The OPO produces an 85 nm (10 THz) wide frequency comb centered at 1.6 μm. Stable long-term operation with >100 mW of average output power has been achieved.
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Affiliation(s)
- Markku Vainio
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki,, Helsinki, Finland.
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45
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Affiliation(s)
- P. Parkkinen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki,
Finland
| | - S. Riikonen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki,
Finland
| | - L. Halonen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki,
Finland
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46
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Salmi T, Sälli E, Halonen L. A Nine-Dimensional Calculation of the Vibrational OH Stretching and HOH Bending Spectrum of the Water Trimer. J Phys Chem A 2012; 116:5368-74. [DOI: 10.1021/jp3017584] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Teemu Salmi
- Laboratory
of Physical Chemistry, Department of Chemistry,
A.I. Virtasen aukio 1 (P.O. BOX 55), FI-00014, University of Helsinki, Finland
| | - Elina Sälli
- Laboratory
of Physical Chemistry, Department of Chemistry,
A.I. Virtasen aukio 1 (P.O. BOX 55), FI-00014, University of Helsinki, Finland
| | - Lauri Halonen
- Laboratory
of Physical Chemistry, Department of Chemistry,
A.I. Virtasen aukio 1 (P.O. BOX 55), FI-00014, University of Helsinki, Finland
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47
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Affiliation(s)
- Lauri Partanen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014
Finland
| | - Vesa Hänninen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014
Finland
| | - Lauri Halonen
- Laboratory of Physical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014
Finland
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Salmi T, Hänninen V, Garden AL, Kjaergaard HG, Tennyson J, Halonen L. Correction to “Calculation of the O–H Stretching Vibrational Overtone Spectrum of the Water Dimer”. J Phys Chem A 2011. [DOI: 10.1021/jp210675h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Vainio M, Ozanam C, Ulvila V, Halonen L. Tuning and stability of a singly resonant continuous-wave optical parametric oscillator close to degeneracy. Opt Express 2011; 19:22515-22527. [PMID: 22109130 DOI: 10.1364/oe.19.022515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Wavelength tuning and stability characteristics of a singly resonant continuous-wave optical parametric oscillator (cw OPO) in the proximity of signal-idler degeneracy have been studied. The OPO is made singly resonant by using a Bragg grating as a spectral filter in the OPO cavity. The signal-idler frequency difference can be tuned from 0.5 to 7 THz, which makes the OPO suitable for cw THz generation by optical heterodyning. The operation of the OPO within this singly-resonant regime is characterized by a strong self-stabilization effect. A gradual transition to an unstable, doubly-resonant regime is observed for a signal-idler detuning smaller than ~0.5 THz.
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Affiliation(s)
- Markku Vainio
- Laboratory of Physical Chemistry, Department of Chemistry, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014, University of Helsinki, Finland.
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Abstract
A simple method for absolute-frequency measurements of molecular transitions in the mid-IR region is reported. The method is based on a cw singly resonant optical parametric oscillator (SRO), which is tunable from 3.2 to 3.45 μm. The mid-IR frequency of the SRO is referenced to an optical frequency comb through its pump and signal beams. Sub-Doppler spectroscopy and absolute-frequency measurement of the P(7) transition of the ν3 band of CH4 are demonstrated.
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Affiliation(s)
- Markku Vainio
- Centre for Metrology and Accreditation (MIKES), P. O. Box 9, FIN-02151 Espoo, Finland.
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