Publications (2024)
Total peer-reviewed articles: 132
Quantum and statistical state-to-state studies of cold Ar + H2+ collisions
Authors: Konings, Maarten; Gonzalez-Lezana, Tomas; Camps, Simen; Loreau, Jerome
Journal: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Publication date: 2024/08/28
DOI: 10.1039/d4cp02179g
Abstract: In this work we present new state-to-state integral scattering cross sections and initial-state selected rate coefficients for the Ar-36 (S-1) + H-2(+) (X-2 Sigma(+)(g),v = 0,j) reactive system for collision energies up to 0.1 eV (with respect to the Ar-36 (S-1) + H-2(+) (X-2 Sigma(+)(g),v = 0,j = 0) channel). To the best of our knowledge, these cross sections are the first fully state resolved ones that were obtained by performing time-independent quantum mechanical and quantum statistical calculations. For this purpose a new full-dimensional ground state (2)A ‘ adiabatic electronic potential energy surface was calculated at the MRCI+Q/aug-cc-pVQZ level of theory, which was fitted by means of machine learning methods. We find that a statistical quantum method and a statistical adiabatic channel model reproduce quantum mechanical initial-state selected cross sections fairly well, thus suggesting that complex-forming mechanisms seem to be playing an important role in the reaction dynamics of the reaction that was studied.
Random matrix theory approach to quantum Fisher information in quantum ergodic systems
Authors: Pavlov, Venelin P.; Chorbadzhiyska, Yoana R.; Nation, Charlie; Porras, Diego; Ivanov, Peter A.
Journal: PHYSICAL REVIEW E
Publication date: 2024/08/26
DOI: 10.1103/PhysRevE.110.024135
Abstract: We theoretically investigate quantum parameter estimation in quantum chaotic systems. Our analysis is based on an effective description of quantum ergodic systems in terms of a random matrix Hamiltonian. Based on this approach, we derive an analytical expression for the time evolution of the quantum Fisher information (QFI), which we find to have three distinct timescales. Initially, the QFI increase is quadratic in time, characterizing the timescale over which initial information is extractable from local measurements only. This quickly passes into linear increase with slope determined by the decay rate of the measured spin observable. When the information is fully spread among all degrees of freedom, a second quadratic timescale determines the long-time behavior of the QFI. We test our random matrix theory prediction with the exact diagonalization of a nonintegrable spin system, focusing on the estimation of a local magnetic field by measurements of the many-body state. Our numerical calculations agree with the effective random matrix theory approach and show that the information on the local Hamiltonian parameter is distributed throughout the quantum system during the quantum thermalization process.
The rich interstellar reservoir of dinitriles: Detection of malononitrile and maleonitrile in TMC-1
Authors: Agundez, M.; Bermudez, C.; Cabezas, C.; Molpeceres, G.; Endo, Y.; Marcelino, N.; Tercero, B.; Guillemin, J. -C.; de Vicente, P.; Cernicharo, J.
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/08/22
DOI: 10.1051/0004-6361/202451525
Abstract: While the nitrile group is by far the most prevalent one among interstellar molecules, the existence of interstellar dinitriles (molecules containing two -CN groups) has recently been proven. Here we report the discovery of two new dinitriles in the cold dense cloud TMC-1. These newly identified species are malononitrile, CH2(CN)(2), and maleonitrile, the Z isomer of NC-CH=CH-CN, which can be seen as the result of substituting two H atoms with two -CN groups in methane and ethylene, respectively. These two molecules were detected using data from the ongoing QUIJOTE line survey of TMC-1 that is being carried out with the Yebes 40 m telescope. We derive column densities of 1.8 x 10(11) cm(-2) and 5.1 x 10(10) cm(-2) for malononitrile and maleonitrile, respectively. This means that they are eight and three times less abundant than HCC-CH2-CN and (E)-HCC-CH=CH-CN, respectively, which are analog molecules detected in TMC-1 in which one -CN group is converted into a -CCH group. This is in line with previous findings in which -CCH derivatives are more abundant than the -CN counterparts in TMC-1. We examined the potential chemical pathways to these two dinitriles, and we find that while maleonitrile can be efficiently formed through the reaction of CN with CH2CHCN, the formation of malononitrile is not clear because the neutral-neutral reactions that could potentially form it are not feasible under the physical conditions of TMC-1.
Gas phase Elemental abundances in Molecular cloudS (GEMS): X. Observational effects of turbulence on the chemistry of molecular clouds
Authors: Beitia-Antero, L.; Fuente, A.; Navarro-Almaida, D.; de Castro, A. I. Gomez; Wakelam, V.; Caselli, P.; Le Gal, R.; Esplugues, G.; Riviere-Marichalar, P.; Spezzano, S.; Pineda, J. E.; Rodriguez-Baras, M.; Canet, A.; Martin-Domenech, R.; Roncero, O.
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/08/20
DOI: 10.1051/0004-6361/202346955
Abstract: Context. We explore the chemistry of the most abundant C-, O-, S-, and N-bearing species in molecular clouds, in the context of the IRAM 30 m Large Programme Gas phase Elemental abundances in Molecular Clouds (GEMS). Thus far, we have studied the impact of the variations in the temperature, density, cosmic-ray ionisation rate, and incident UV field in a set of abundant molecular species. In addition, the observed molecular abundances might be affected by turbulence which needs to be accounted for in order to have a more accurate description of the chemistry of interstellar filaments. Aims. In this work, we aim to assess the limitations introduced in the observational works when a uniform density is assumed along the line of sight for fitting the observations, developing a very simple numerical model of a turbulent box. We searched for any observational imprints that might provide useful information on the turbulent state of the cloud based on kinematical or chemical tracers. Methods. We performed a magnetohydrodynamical (MHD) simulation in order to reproduce the turbulent steady state of a turbulent box with properties typical of a molecular filament before collapse. We post-processed the results of the MHD simulation with a chemical code to predict molecular abundances, and then post-processed this cube with a radiative transfer code to create synthetic emission maps for a series of rotational transitions observed during the GEMS project. Results. From the kinematical point of view, we find that the relative alignment between the observer and the mean magnetic field direction affect the observed line profiles, obtaining larger line widths for the case when the line of sight is perpendicular to the magnetic field. These differences might be detectable even after convolution with the IRAM 30 m efficiency for a nearby molecular cloud. From the chemical point of view, we find that turbulence produces variations for the predicted abundances, but they are more or less critical depending on the chosen transition and the chemical age. When compared to real observations, the results from the turbulent simulation provides a better fit than when assuming a uniform gas distribution along the line of sight. Conclusions. In the view of our results, we conclude that taking into account turbulence when fitting observations might significantly improve the agreement with model predictions. This is especially important for sulfur bearing species which are very sensitive to the variations of density produced by turbulence at early times (0.1 Myr). The abundance of CO is also quite sensitive to turbulence when considering the evolution beyond a few 0.1 Myr.
Space and laboratory discovery of iminopentadienylidene, HNC5
Authors: Fuentetaja, R.; Cabezas, C.; Endo, Y.; Agundez, M.; Tercero, B.; Marcelino, N.; de Vicente, P.; Cernicharo, J.
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/08/15
DOI: 10.1051/0004-6361/202451319
Abstract: We report the discovery of HNC5 in TMC-1. Six lines have been found in harmonic relation, with quantum numbers J = 12-11 up to J = 17-16. The lines can be reproduced with the standard frequency relation for linear molecules with B = 1361.75034 +/- 0.00033 MHz and D = 32.2 +/- 0.7 Hz. The assignment of the carrier to iminopentadienylidene was achieved through examining the possible candidates at a high level of theoretical ab initio calculations. Motivated by the good agreement between the observed B and the calculated value for HNC5, we searched for it in the laboratory and observed the transitions J = 5-4 to 7-6. The derived rotational and distortion constants are 1361.74998 +/- 0.00040 MHz and 26.5 +/- 5.5 Hz, respectively. Hence, we solidly conclude that the carrier of the lines found in TMC-1 is HNC5. The calculated dipole moment for this species is 7.7 D and the derived column density is (1.3 +/- 0.2) x 10(10) cm(-2). We used the new QUIJOTE data to improve previous observations of HC4NC and found that the abundance ratio HC4NC/HNC5 is 10 +/- 2. The abundance ratio of HC5N and its two isomers HC4NC and HNC5 is 500 +/- 80 and 5100 +/- 800, respectively. These abundance ratios are higher by a factor of similar to 10 than those of the equivalent isomers of HC3N. Chemical models reproduce the observed abundances reasonably well when a chemistry similar to that of the smaller species C3HN isomers is adopted. The formation of HNC5 and HC4NC arises from the dissociative recombination with electrons of the cations HC5NH+ and HC4NCH+.
Dissociative photoionization of acetaldehyde in the 10.2-19.5 eV VUV range
Authors: Recio, Pedro; Bello, Roger Y.; Garcia, Gustavo A.; Zanchet, Alexandre; Gonzalez-Vazquez, Jesus; Banares, Luis; Poullain, Sonia Marggi
Journal: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Publication date: 2024/08/14
DOI: 10.1039/d4cp01984a
Abstract: The valence-shell dissociative photoionization of acetaldehyde has been investigated by means of the photoion photoelectron coincidence technique in conjunction with tuneable synchrotron radiation. The experimental results consist of threshold photoelectron spectra for the parent ion and for each fragment ion in the 10.2-19.5 eV photon energy range, along with (ion, e) kinetic energy coincidence diagrams obtained from measurements at fixed photon energies. The results are complemented by high-level ab initio calculations of potential energy curves as a function of the C-H bond distance. The nudged elastic band (NEB) method has been employed to connect the parent ion Franck-Condon region to the formation of the HCO+, CH3+ and CH4+ ion fragments. Appearance energies have been determined for six fragment ions with an improved accuracy, including two fragmentation channels, which to the best of our knowledge have not been reported previously, i.e. the formation of CH2CO+, lying at 13.10 +/- 0.05 eV, and the formation of CH2+ at 15.1 +/- 0.1 eV. Based on both experimental and theoretical results, the dissociation dynamics following ionization of acetaldehyde into the different fragmentation channels are discussed. The energetics and dynamics of the state-selected dissociation of acetaldehyde cation prepared by one-photon valence shell ionization are studied via a combined experimental and high-level ab initio theoretical approach.
The temperature variation of the CH+ + H reaction rate coefficients: a puzzle finally understood?
Authors: Jara-Toro, Rafael A.; Roncero, Octavio; Lique, Francois
Journal: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Publication date: 2024/08/14
DOI: 10.1039/d4cp01902d
Abstract: CH+ was the first molecular ion identified in the interstellar medium and is found to be ubiquitous in interstellar clouds. However, its formation and destruction paths are not well understood, especially at low temperatures. A new theoretical approach based on the canonical variational transition state theory was used to study the H + CH+ reactive collisions. Rate coefficients for formation of C+ ions are calculated as a function of temperature. We considered the participation of a direct path and an indirect path in which the reactants should overcome an entropic barrier to form a van der Waals complex or pass through a CH2+ intermediate complex, respectively. We show that the contribution of both pathways to the formation of C+ has to be taken into account. The new reactive rate coefficients for the title reaction, complemented by reactive data for CH+/CH2+ in the H/H2/He mixture, have been used to simulate the corresponding kinetics experimentally measured using an Atomic Beam 22 Pole Trap apparatus at low temperature. A good agreement with the experimental findings was found at 50 K. At a lower temperature, the model overestimates the formation of C+. This shows that secondary reactions are not responsible for the weak C+ production in the experiments at such temperature. Then, we discuss the possible impact of non-adiabatic effects in the study of the H + CH+ reactive collisions and we found that such effects can be responsible for the decrease of the H + CH+ rate coefficients at low temperature. This study offers an explanation for the disagreement between H + CH+ theoretical and experimental rate coefficients which has been going on for 20 years and highlights the need for performing non-adiabatic studies for this simple chemical reaction.
Enhanced formation of interstellar complex organic molecules on carbon monoxide ice
Authors: Molpeceres, G.; Furuya, K.; Aikawa, Y.
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/08/13
DOI: 10.1051/0004-6361/202449604
Abstract: We investigated the role of carbon monoxide ice in the chemical evolution of prestellar cores using astrochemical rate equation models. We constrained the ratios of the binding energies on CO ice and H2O ice for a series of adsorbates deemed important in diffusive chemistry on H2O ices. We later included these ratios in our chemical reaction network model, where the binding and diffusion energies of icy species vary as a function of the surface composition. When the surface coverage of CO increases, the model shows an enhancement of O-bearing complex organic molecules especially those that formed from the intermediate products of CO hydrogenation (e.g., HCO) and CH3/CH2. Because the binding energy of CH3/CH2 is in the right range, its diffusion rate increases significantly with CO coverage. At T >14 K and with less influence, enhanced diffusion of HCO also contributes to the increase in the abundances of complex organic molecules. We find, however, that chemistry is not always enhanced on CO ice and that the temperature and cosmic ray ionization rate of each astronomical object is crucial for this particular chemistry, revealing a highly non trivial behavior that needs to be addressed on a per-case basis. Our results are highly relevant in the context of interstellar ice observations with JWST.
Non-Markovianity in High-Dimensional Open Quantum Systems using Next-generation Multicore Optical Fibers
Authors: Rojas-Rojas, Santiago; Martinez, Daniel; Sawada, Kei; Pereira, Luciano; Walborn, Stephen P.; Gomez, Esteban S.; Bernardes, Nadja K.; Lima, Gustavo
Journal: QUANTUM
Publication date: 2024/08/12
Abstract: With the advent of quantum technology, the interest in communication tasks assisted by quantum systems has increased both in academia and industry. Nonetheless, the transmission of a quantum state in real-world scenarios is bounded by environmental noise, so that the quantum channel is an open quantum system. In this work, we study a high-dimensional open quantum system in a multicore optical fiber by characterizing the environmental interaction as quantum operations corresponding to probabilistic phase-flips. The experimental platform is currently state-of-the-art for quantum information processing with multicore fibers. At a given evolution stage we observe a non-Markovian behaviour of the system, which is demonstrated through a proof-of-principle implementation of the Quantum Vault protocol. A better understanding of phase-noise in multicore fibers will improve several real-world communication protocols, since they are a prime candidate to be adopted in future telecom networks.
Discovery of HCCCH2CCH in TMC-1 with the QUIJOTE line survey
Authors: Fuentetaja, R.; Agundez, M.; Cabezas, C.; Tercero, B.; Marcelino, N.; Pardo, J. R.; de Vicente, P.; Cernicharo, J.
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/08/08
DOI: 10.1051/0004-6361/202348777
Abstract: We present the first detection in space of 1,4-pentadiyne. It has been found towards TMC-1 with the QUIJOTE line survey in the 31-50 GHz range. We observed a total of 17 transitions with J = 2 up to 13 and K-a = 0, 1 and 2. The observed transitions allowed us to derive a rotational temperature of 9.5 +/- 0.5 K and a column density of (5.0 +/- 0.5) x 10(12) cm(-2). This molecule was the last non-cyclic isomer of the C5H4 family that could be detected via radio astronomy. A computational chemistry study was performed to determine the energies of the five most stable isomers. The isomer (c-C3H3CCH) has a considerably higher energy than the others, and it has not yet been detected. To better understand the chemical reactions involving these species, we compared the ethynyl and cyano derivatives. The observed abundances of these species are in good agreement with the branching ratios of the formation reactions studied with our chemical model of TMC-1.
More sulphur in TMC-1: Discovery of the NC3S and HC3S radicals with the QUIJOTE line survey
Authors: Cernicharo, J.; Cabezas, C.; Agundez, M.; Fuentetaja, R.; Tercero, B.; Marcelino, N.; de Vicente, P.
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/08/07
DOI: 10.1051/0004-6361/202451256
Abstract: We present the detection of the free radicals NC3S and HC3S towards TMC-1 with the QUIJOTE line survey. The derived column densities are (1.4 +/- 0.2)x10(11) for NC3S and (1.5 +/- 0.2)x10(11) for HC3S. We searched for NCCS, but only three transitions are within the domain of our QUIJOTE line survey and the observed lines are marginally detected at the 3 sigma level, providing an upper limit to its column density of <= 6 x 10(10) cm(-2). We also unsuccessfully searched for longer species of the NCnS (n >= 4) and HCnS (n >= 5) families in our TMC-1 data. A chemical model based on a reduced set of reactions involving HC3S and NC3S predicts abundances that are 10-100 times below the observed values. These calculations indicate that the most efficient reactions of formation of HC3S and NC3S in the model are S + C3H2 and N + HC3S, respectively, while both radicals are very efficiently destroyed through reactions with neutral atoms.
Dust beyond the torus: revealing the mid-infrared heart of local Seyfert ESO 428-G14 with JWST/MIRI
Authors: Haidar, Houda; Rosario, David J.; Alonso-Herrero, Almudena; Pereira-Santaella, Miguel; Garcia-Bernete, Ismael; Campbell, Stephanie; Hoenig, Sebastian F.; Ramos Almeida, Cristina; Hicks, Erin; Delaney, Daniel; Davies, Richard; Ricci, Claudio; Harrison, Chris M.; Leist, Mason; Lopez-Rodriguez, Enrique; Garcia-Burillo, Santiago; Zhang, Lulu; Packham, Chris; Gandhi, Poshak; Audibert, Anelise; Bellocchi, Enrica; Boorman, Peter; Bunker, Andrew; Combes, Francoise; Santos, Tanio Diaz; Donnan, Fergus R.; Martin, Omaira Gonzalez; Munoz, Laura Hermosa; Charidis, Matthaios; Labiano, Alvaro; Levenson, Nancy A.; May, Daniel; Rigopoulou, Dimitra; Ardila, Alberto Rodriguez; Shimizu, T. Taro; Stalevski, Marko; Ward, Martin
Journal: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Publication date: 2024/08/06
Abstract: Polar dust has been discovered in a number of local active galactic nuclei (AGN), with radiation-driven torus models predicting a wind to be its main driver. However, little is known about its characteristics, spatial extent, or connection to the larger scale outflows. We present the first JWST/MIRI study aimed at imaging polar dust by zooming on to the centre of ESO 428-G14, part of the Galaxy Activity, Torus, and Outflow Survey (GATOS) survey of local AGN. We detect extended mid-infrared (MIR) emission within 200 pc from the nucleus. This polar structure is co-linear with a radio jet and lies perpendicular to a molecular gas lane that feeds and obscures the nucleus. Its morphology bears a striking resemblance to that of gas ionized by the AGN in the narrow-line region. We demonstrate that part of this spatial correspondence is due to contamination within the JWST filter bands from strong emission lines. Correcting for the contamination, we find the morphology of the dust continuum to be more compact, though still clearly extended out to $rapprox 100 , rm pc$. We estimate the emitting dust has a temperature of $sim 120, rm K$. Using simple models, we find that the heating of small dust grains by the radiation from the central AGN and/or radiative jet-induced shocks is responsible for the extended MIR emission. Radiation-driven dusty winds from the torus is unlikely to be important. This has important implications for scales to which AGN winds can carry dust and dense gas out into their host galaxies.
Detecting Entanglement from Macroscopic Measurements of the Electric Field and Its Fluctuations
Authors: Rosario, Pedro; Santos, Alan C.; Piovella, Nicola; Kaiser, Robin; Cidrim, Andre; Bachelard, Romain
Journal: PHYSICAL REVIEW LETTERS
Publication date: 2024/07/31
DOI: 10.1103/PhysRevLett.133.050203
Abstract: To address the outstanding task of detecting entanglement in large quantum systems, entanglement witnesses have emerged, addressing the separable nature of a state. Yet optimizing witnesses, or accessing them experimentally, often remains a challenge. We here introduce a family of entanglement witnesses for open quantum systems. Based on the electric field, it does not require state tomography or single-site addressing, but rather macroscopic measurements of the field quadratures and of the total fluorescence. Its efficiency is demonstrated by detecting, from almost any direction, the entanglement of collective singlephoton states, such as long-lived states generated by cooperative spontaneous emission. Able to detect entanglement in large open quantum systems, and through a single continuous measurement if operating in the stationary regime, these electric-field-based witnesses can be used on any set of emitters described by the Pauli group, such as atomic systems (cold atoms and trapped ions), giant atoms, color centers, and superconducting qubits.
Discovery of the interstellar cyanoacetylene radical cation HC3N+
Authors: Cabezas, C.; Agundez, M.; Endo, Y.; Tercero, B.; Marcelino, N.; de Vicente, P.; Cernicharo, J.
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/07/30
DOI: 10.1051/0004-6361/202451081
Abstract: We report the first identification in space of HC3N+, the simplest member of the family of cyanopolyyne cations. Three rotational transitions with half-integer quantum numbers from J = 7/2 to 11/2 have been observed with the Yebes 40 m radio telescope and assigned to HC3N+, which has an inverted 2 Pi ground electronic state. The three rotational transitions exhibit several hyperfine components due to the magnetic and nuclear quadrupole coupling effects of the H and N nuclei. We confidently assign the characteristic rotational spectrum pattern to HC3N+ based on the good agreement between the astronomical and theoretical spectroscopic parameters. We derived a column density of (6.0 +/- 0.6)x10(10) cm(-2) and a rotational temperature of 4.5 +/- 1 K. The abundance ratio between HC3N and HC3N+ is 3200 +/- 320. As found for the larger members of the family of cyanopolyyne cations (HC5N+ and HC7N+), HC3N+ is mainly formed through the reactions of H-2 and the cation C3N+ and by the reactions of H+ with HC3N. In the same manner than other cyanopolyyne cations, HC3N+ is mostly destroyed through a reaction with H-2 and a dissociative recombination with electrons.
Multiline observations of hydrogen, helium, and carbon radio-recombination lines toward Orion A: A detailed dynamical study and direct determination of physical conditions
Authors: Pabst, C. H. M.; Goicoechea, J. R.; Cuadrado, S.; Salas, P.; Tielens, A. G. G. M.; Marcelino, N.
Journal: ASTRONOMY & ASTROPHYSICS
Publication date: 2024/07/29
DOI: 10.1051/0004-6361/202347574
Abstract: We present a study of hydrogen, helium, and carbon millimeter-wave radio-recombination lines (RRLs) toward 10 representative positions throughout the Orion Nebula complex, using the Yebes 40 m telescope in the Q band (31.3 GHz to 50.6 GHz) at an angular resolution of about 45 ” (similar to 0.09 pc). The observed positions include the Orion Nebula (M42) with the Orion Molecular Core 1, M43, and the Orion Molecular Core 3 bordering on NGC 1973, 1975, and 1977. While hydrogen and helium RRLs arise in the ionized gas surrounding the massive stars in the Orion Nebula complex, carbon RRLs stem from the neutral gas of the adjacent photo-dissociation regions (PDRs). The high velocity resolution (0.3 km s(-1)) enables us to discern the detailed dynamics of the RRL emitting neutral and ionized gas. We compare the carbon RRLs with SOFIA/upGREAT observations of the [C II] 158 mu m line and IRAM 30 m observations of the (CO)-C-13 (J = 2-1) line (the complete map is presented here for the first time). We observe small differences in peak velocities between the different tracers, which cannot always be attributed to geometry but potentially to shear motions. Using the far-infrared [C II] and [C-13 II] intensities with the carbon RRL intensities, we can infer physical conditions (electron temperature T-e and electron density n(e), converted to hydrogen nuclei density n(H) by dividing by the carbon gas-phase abundance A(C) similar or equal to 1.4 x 10(-4)) in the PDR gas using nonlocal thermal equilibrium excitation models. For positions in OMC1, we infer n(e) similar or equal to 20-40 cm(-3) and T-e similar or equal to 210-240 K. On the border between OMC1 and M43, we observe two gas components with n(e) similar or equal to 2 cm(-3) and n(e) similar or equal to 8 cm(-3), and T-e similar or equal to 100 K and T-e similar or equal to 150 K. In M43, we infer n(e) similar or equal to 2-3 cm(-3) and T-e similar or equal to 140 K. The Extended Orion Nebula southeast of OMC1 is characterized by n(e) similar or equal to 2 cm(-3) and T-e similar or equal to 180 K, while OMC3 has n(e) similar or equal to 1 cm(-3) and T-e similar or equal to 130 K. Our observations are sensitive enough to detect faint lines toward two positions in OMC1, in the BN/KL PDR and the PDR close to the Trapezium stars, that may be attributed to RRLs of C+ or O+. In general, the RRL line widths of both the ionized and neutral gas, as well as the [C II] and (CO)-C-13 line widths, are broader than thermal, indicating significant turbulence in the interstellar medium, which transitions from super-Alfvenic and subsonic in the ionized gas to sub-Alfvenic and supersonic in the molecular gas. At the scales probed by our observations, the turbulent pressure dominates the pressure balance in the neutral and molecular gas, while in the ionized gas the turbulent pressure is much smaller than the thermal pressure.