Genera of phytopathogenic fungi: GOPHY 4.

This paper is the fourth contribution in the Genera of Phytopathogenic Fungi (GOPHY) series. The series provides morphological descriptions and information about the pathology, distribution, hosts and disease symptoms, as well as DNA barcodes for the taxa covered. Moreover, 12 whole-genome sequences for the type or new species in the treated genera are provided. The fourth paper in the GOPHY series covers 19 genera of phytopathogenic fungi and their relatives, including Ascochyta, Cadophora, Celoporthe, Cercospora, Coleophoma, Cytospora, Dendrostoma, Didymella, Endothia, Heterophaeomoniella, Leptosphaerulina, Melampsora, Nigrospora, Pezicula, Phaeomoniella, Pseudocercospora, Pteridopassalora, Zymoseptoria, and one genus of oomycetes, Phytophthora. This study includes two new genera, 30 new species, five new combinations, and 43 typifications of older names. Taxonomic novelties: New genera: Heterophaeomoniella L. Mostert, C.F.J. Spies, Halleen & Gramaje, Pteridopassalora C. Nakash. & Crous; New species: Ascochyta flava Qian Chen & L. Cai, Cadophora domestica L. Mostert, R. van der Merwe, Halleen & Gramaje, Cadophora rotunda L. Mostert, R. van der Merwe, Halleen & Gramaje, Cadophora vinacea J.R. Úrbez-Torres, D.T. O'Gorman & Gramaje, Cadophora vivarii L. Mostert, Havenga, Halleen & Gramaje, Celoporthe foliorum H. Suzuki, Marinc. & M.J. Wingf., Cercospora alyssopsidis M. Bakhshi, Zare & Crous, Dendrostoma elaeocarpi C.M. Tian & Q. Yang, Didymella chlamydospora Qian Chen & L. Cai, Didymella gei Qian Chen & L. Cai, Didymella ligulariae Qian Chen & L. Cai, Didymella qilianensis Qian Chen & L. Cai, Didymella uniseptata Qian Chen & L. Cai, Endothia cerciana W. Wang. & S.F. Chen, Leptosphaerulina miscanthi Qian Chen & L. Cai, Nigrospora covidalis M. Raza, Qian Chen & L. Cai, Nigrospora globospora M. Raza, Qian Chen & L. Cai, Nigrospora philosophiae-doctoris M. Raza, Qian Chen & L. Cai, Phytophthora transitoria I. Milenkovic, T. Májek & T. Jung, Phytophthora panamensis T. Jung, Y. Balci, K. Broders & I. Milenkovic, Phytophthora variabilis T. Jung, M. Horta Jung & I. Milenkovic, Pseudocercospora delonicicola C. Nakash., L. Suhaizan & I. Nurul Faziha, Pseudocercospora farfugii C. Nakash., I. Araki, & Ai Ito, Pseudocercospora hardenbergiae Crous & C. Nakash., Pseudocercospora kenyirana C. Nakash., L. Suhaizan & I. Nurul Faziha, Pseudocercospora perrottetiae Crous, C. Nakash. & C.Y. Chen, Pseudocercospora platyceriicola C. Nakash., Y. Hatt, L. Suhaizan & I. Nurul Faziha, Pseudocercospora stemonicola C. Nakash., Y. Hatt., L. Suhaizan & I. Nurul Faziha, Pseudocercospora terengganuensis C. Nakash., Y. Hatt., L. Suhaizan & I. Nurul Faziha, Pseudocercospora xenopunicae Crous & C. Nakash.; New combinations: Heterophaeomoniella pinifoliorum (Hyang B. Lee et al.) L. Mostert, C.F.J. Spies, Halleen & Gramaje, Pseudocercospora pruni-grayanae (Sawada) C. Nakash. & Motohashi., Pseudocercospora togashiana (K. Ito & Tak. Kobay.) C. Nakash. & Tak. Kobay., Pteridopassalora nephrolepidicola (Crous & R.G. Shivas) C. Nakash. & Crous, Pteridopassalora lygodii (Goh & W.H. Hsieh) C. Nakash. & Crous; Typification: Epitypification: Botrytis infestans Mont., Cercospora abeliae Katsuki, Cercospora ceratoniae Pat. & Trab., Cercospora cladrastidis Jacz., Cercospora cryptomeriicola Sawada, Cercospora dalbergiae S.H. Sun, Cercospora ebulicola W. Yamam., Cercospora formosana W. Yamam., Cercospora fukuii W. Yamam., Cercospora glochidionis Sawada, Cercospora ixorana J.M. Yen & Lim, Cercospora liquidambaricola J.M. Yen, Cercospora pancratii Ellis & Everh., Cercospora pini-densiflorae Hori & Nambu, Cercospora profusa Syd. & P. Syd., Cercospora pyracanthae Katsuki, Cercospora horiana Togashi & Katsuki, Cercospora tabernaemontanae Syd. & P. Syd., Cercospora trinidadensis F. Stevens & Solheim, Melampsora laricis-urbanianae Tak. Matsumoto, Melampsora salicis-cupularis Wang, Phaeoisariopsis pruni-grayanae Sawada, Pseudocercospora angiopteridis Goh & W.H. Hsieh, Pseudocercospora basitruncata Crous, Pseudocercospora boehmeriigena U. Braun, Pseudocercospora coprosmae U. Braun & C.F. Hill, Pseudocercospora cratevicola C. Nakash. & U. Braun, Pseudocercospora cymbidiicola U. Braun & C.F. Hill, Pseudocercospora dodonaeae Boesew., Pseudocercospora euphorbiacearum U. Braun, Pseudocercospora lygodii Goh & W.H. Hsieh, Pseudocercospora metrosideri U. Braun, Pseudocercospora paraexosporioides C. Nakash. & U. Braun, Pseudocercospora symploci Katsuki & Tak. Kobay. ex U. Braun & Crous, Septogloeum punctatum Wakef.; Neotypification: Cercospora aleuritis I. Miyake; Lectotypification: Cercospora dalbergiae S.H. Sun, Cercospora formosana W. Yamam., Cercospora fukuii W. Yamam., Cercospora glochidionis Sawada, Cercospora profusa Syd. & P. Syd., Melampsora laricis-urbanianae Tak. Matsumoto, Phaeoisariopsis pruni-grayanae Sawada, Pseudocercospora symploci Katsuki & Tak. Kobay. ex U. Braun & Crous. Citation: Chen Q, Bakhshi M, Balci Y, Broders KD, Cheewangkoon R, Chen SF, Fan XL, Gramaje D, Halleen F, Horta Jung M, Jiang N, Jung T, Májek T, Marincowitz S, Milenkovic T, Mostert L, Nakashima C, Nurul Faziha I, Pan M, Raza M, Scanu B, Spies CFJ, Suhaizan L, Suzuki H, Tian CM, Tomsovský M, Úrbez-Torres JR, Wang W, Wingfield BD, Wingfield MJ, Yang Q, Yang X, Zare R, Zhao P, Groenewald JZ, Cai L, Crous PW (2022). Genera of phytopathogenic fungi: GOPHY 4. Studies in Mycology 101: 417-564. doi: 10.3114/sim.2022.101.06.

A phylogenetic study of Dothiorella and Spencermartinsia species associated with woody plants in Iran, New Zealand, Portugal and Spain.

Dothiorella and Spencermartinsia are two botryosphaeriaceous genera with dark 2-celled conidia and found in parasitic, saprophytic or endophytic association with various woody host plants. Based on ITS and EF1-α sequence data and morphology, eight new species are described from Iran, New Zealand, Portugal and Spain. Of these, five species are placed in Dothiorella, namely D. iranica, D. parva, D. prunicola, D. sempervirentis and D. striata, and three species belong to Spencermartinsia named as S. citricola, S. mangiferae and S. plurivora. An identification key to the species of each genus is provided.

New species of Colletotrichum from wild Poaceae and Cyperaceae plants in Iran.

Twenty-two Colletotrichum strains were isolated from anthracnose symptoms or leaf spots on leaves of various wild Poaceae and Cyperaceae plants collected in three provinces of Iran and tentatively identified as belonging to the Graminicola species complex based on morphology. All strains were studied via a polyphasic approach combining colony characteristics, morphology and phylogeny inferred from multi-locus sequences, including the nuc rDNA ITS1-5.8S-ITS2 (ITS), partial sequences of the ß-tubulin (tub2), actin (act), manganese superoxide dismutase 2 (sod2), DNA lyase 2 (apn2) genes, a 200-bp intron of the glyceraldehyde-3-phosphate dehydrogenase (gapdh), and the intergenic spacer between the apn2 gene and the mat1 idiomorph (apn2/mat1). Six species were distinguished, including three new species, namely C. caspicum, C. persicum, and C. sacchari, and three previously described species, C. cereale, C. nicholsonii and C. sublineola. Comprehensive morphological descriptions and illustrations are provided for all species. Furthermore, this study provided new insights into the distribution and host range of known species.

Fusarium and allied fusarioid taxa (FUSA). 1.

Seven Fusarium species complexes are treated, namely F. aywerte species complex (FASC) (two species), F. buharicum species complex (FBSC) (five species), F. burgessii species complex (FBURSC) (three species), F. camptoceras species complex (FCAMSC) (three species), F. chlamydosporum species complex (FCSC) (eight species), F. citricola species complex (FCCSC) (five species) and the F. concolor species complex (FCOSC) (four species). New species include Fusicolla elongata from soil (Zimbabwe), and Neocosmospora geoasparagicola from soil associated with Asparagus officinalis (Netherlands). New combinations include Neocosmospora akasia, N. awan, N. drepaniformis, N. duplosperma, N. geoasparagicola, N. mekan, N. papillata, N. variasi and N. warna. Newly validated taxa include Longinectria gen. nov., L. lagenoides, L. verticilliforme, Fusicolla gigas and Fusicolla guangxiensis. Furthermore, Fusarium rosicola is reduced to synonymy under N. brevis. Finally, the genome assemblies of Fusarium secorum (CBS 175.32), Microcera coccophila (CBS 310.34), Rectifusarium robinianum (CBS 430.91), Rugonectria rugulosa (CBS 126565), and Thelonectria blattea (CBS 952.68) are also announced here. Citation: Crous PW, Sandoval-Denis M, Costa MM, Groenewald JZ, van Iperen AL, Starink-Willemse M, Hernández-Restrepo M, Kandemir H, Ulaszewski B, de Boer W, Abdel-Azeem AM, Abdollahzadeh J, Akulov A, Bakhshi M, Bezerra JDP, Bhunjun CS, Câmara MPS, Chaverri P, Vieira WAS, Decock CA, Gaya E, Gené J, Guarro J, Gramaje D, Grube M, Gupta VK, Guarnaccia V, Hill R, Hirooka Y, Hyde KD, Jayawardena RS, Jeewon R, Jurjevic Z, Korsten L, Lamprecht SC, Lombard L, Maharachchikumbura SSN, Polizzi G, Rajeshkumar KC, Salgado-Salazar C, Shang Q-J, Shivas RG, Summerbell RC, Sun GY, Swart WJ, Tan YP, Vizzini A, Xia JW, Zare R, González CD, Iturriaga T, Savary O, Coton M, Coton E, Jany J-L, Liu C, Zeng Z-Q, Zhuang W-Y, Yu Z-H, Thines M (2022). Fusarium and allied fusarioid taxa (FUSA). 1. Fungal Systematics and Evolution 9: 161-200. doi: 10.3114/fuse.2022.09.08.

False estimates of stimulated Raman pumping efficiency caused by the optical Stark effect.

One technique for measuring the fraction of molecules pumped to the excited state in stimulated Raman pumping (SRP) is to record the depletion of molecules in the lower state by resonance enhanced multiphoton ionization (REMPI). The presence of electric fields on the order of 10(7) V/cm arising from the pulsed SRP laser beams is sufficient to shift the line position of the REMPI transition to such an extent that the estimate of the pumping efficiency is overestimated unless this shift is accounted for.

First Report of Leaf Blotch Caused by Septoria phalaridis on Phalaris paradoxa.

Phalaris paradoxa (hood canarygrass) is one of the most abundant weeds in wheat fields of Iran. In a survey conducted from 2005 to 2007 in Ilam (Dehloran City) and Golestan (Gorgan City) provinces, leaf blotch symptoms were prevalent on P. paradoxa. Initial symptoms were pale brown and necrotic lesions that were 3 to 4 mm long on the leaves. Severity of the disease on the lower leaves was higher than on the upper leaves. Pycnidia were observed on the adaxial surface of infected leaves, scattered or sometimes in clusters, dark brown, globose, and 70 to 90 µm in diameter, with the ostiole approximately 10 µm in diameter. Conidia were filiform, hyaline, 0 to 3 septate (mostly 1 septate), and 17 to 40 × 1.5 to 2.0 µm. Conidiogenesis type was holoblastic. On the basis of the above morphological characters, this species was identified as Septoria phalaridis Cocc. & Morini (2,3). Sequencing the internal transcribed spacer (ITS) region of the fungus (GenBank Accession No. GU123926) showed 98% homology to Mycosphaerella graminicola strain 687 and 97% to S. passerinii strain ATCC26515 (GenBank Accession Nos. AB435068.1 and AF181696.1). To confirm pathogenicity of the fungus, 25 P. paradoxa seedlings were inoculated at the three-leaf stage with 20 ml of 1 × 107 spores/ml suspension with a hand sprayer. Plants were covered with a clear polyethylene bag to increase humidity and prevent cross contamination. After 72 h, bags were removed and plants were kept in a greenhouse at 21 ± 2/16 ± 2°C (day/night) and a 16-h photoperiod. Control plants received sterilized distilled water only. Leaves of each plant were visually inspected every day and the appearance of disease symptoms was recorded. After 1 month, all inoculated leaves showed symptoms and signs of the disease such as chlorosis, necrosis, and pycnidia, whereas control plants showed no symptoms or signs of disease. The infected plant tissues were examined with a microscope, the pycnidia and pycnidiospores were measured, and S. phalaridis was reisolated from leaf lesions. The first description of S. phalaridis was on P. brachystachys (1); however, to our knowledge, this is the first report of this pathogen on P. paradoxa. In addition, this is a new fungal species for the mycobiota of Iran. Two voucher specimens (IRAN 14078 F and IRAN 14218 F) were deposited in the Fungus Collection of the Ministry of Jihad-e Agriculture, Tehran, Iran. References: (1) G. Cocconi and F. Morini. Mem. R. Accad. Sci. Ist. Bologna, Cl. Sci. Fis. Ser. 4, 6:371, 1884. (2) M. J. Priest. Fungi of Australia, Septoria. ABRS, Canberra. CSIRO Publishing, Melbourne, 2006. (3) D. N. Teterevnikova-Babayan. Fungi of the Genus Septoria in the USSR. Akademiya Nauk Armyanskoi SSR, Yerevan, 1987.

Association of Microascus cirrosus (Microascaceae, Ascomycetes) with Brown Leaf Spot of Pistachio in Iran.

Iran is the largest pistachio-producing and exporting country in the world with an annual production of approximately 200,000 t. In July 2009, brown spots were noticed on the leaves of an unknown cultivar of pistachio (Pistacia vera L.) in the Mazhan Region of Birjand, South Khorasan, Iran. Nearly 20% of the trees in the surveyed area (1 ha) showed irregularly shaped leaf spots that were mainly on the abaxial surface, measured 4 to 6 mm in diameter, and were initially pale brown but progressively became dark brown. Lesions were cut from diseased tissues, surface sterilized, and placed on acidified potato dextrose agar (APDA). An anamorphic fungus was consistently isolated from the tissues. The fungus was identified as Microascus cirrosus Curzi (1,4). Colonies on PDA at 25°C reached 9 mm in diameter in 7 days and appeared olivaceous brown and zonate, and perithecia developed in 14 days. Perithecia were black, superficial or partially immersed, spherical, 110 to 200 µm in diameter, with cylindrical necks measuring up to 60 µm long by 25 to 35 µm broad; asci were globose to ovate, eight spored, and 9 to 11 × 8 to 10.5 µm; ascospores were pale reddish brown, variable in shape, ranging from concavo-convex, sometimes plano-convex to oval, and 4.5 to 6 × 3 to 4 µm. The associated anamorph on PDA was a Scopulariopsis sp. with annellophores borne singly or in groups of two or three, 10 to 16 × 2.5 to 3.5 µm, with abruptly narrowed apices; conidia were produced in chains, globose to subglobose, basally truncate, pale olive to fuscous, and 4 to 5 × 3 to 4 µm; chlamydospores were globose to pyriform, terminal or intercalary, and 8.5 to 17.5 µm in long axis. Pathogenicity of two isolates was tested using the filter-paper method of Takahashi et al. (3). Mycelial plugs (5 mm in diameter) as well as filter papers containing conidia were placed on five needle-wounded or nonwounded attached leaves of pistachio cv. Kale-Ghuchi in triplicate. The leaves were covered with a translucent plastic bag for 4 days. Inoculated detached and inoculated wounded attached leaves showed symptoms after 6 and 9 days on 5-month-old and 2-month-old leaves, respectively. Control leaves (five in triplicate) remained symptomless. The pathogen was frequently reisolated from the margins of the lesions. To our knowledge, this is the first record of M. cirrosus occurring on pistachio as well as the first report of a member of this genus from Iran. The same fungus has been reported as the causal agent of stored corn deterioration in the United States (1). M. cirrosus also produced a dimorphic yeast phase on PDA but not on malt extract agar or water agar. Cultures with partial reversion developed chlamydospore-like cells. Higher temperatures (25 to 30°C) and surface-sterilized pistachio leaves placed on PDA accelerated the reversion of the yeast phase to hyphal phase. Although dimorphism has been reported in other plant pathogenic fungi (2), this is the first report of dimorphism in this fungus and of a dimorphic fungus attacking pistachio. Further investigations are needed to determine the relation between dimorphism and pathogenicity. A culture (IRAN 1497 C) of the fungus is preserved by R. Zare. References: (1) G. L. Barron et al. Can. J. Bot. 39:1609, 1961. (2) M. Nadal et al. FEMS Microbiol. Lett. 284:127, 2008. (3) W. Takahashi et al. J. Plant Pathol. 91:171, 2009. (4) J. A. von Arx. Persoonia 8:191, 1975.

Taxonomy and phylogeny of cercosporoid ascomycetes on Diospyros spp. with special emphasis on Pseudocercospora spp.

A worldwide survey of cercosporoid ascomycete species on hosts of the genus Diospyros (persimmon) with key to the species based on characters in vivo is provided. Special emphasis is placed on species of the genus Pseudocercospora, which are in part also phylogenetically analysed, using a multilocus approach. Species of the latter genus proved to be very diverse, with a remarkable degree of cryptic speciation. Seven new species are described (Pseudocercospora diospyri-japonicae, P. diospyriphila, P. ershadii, P. kakiicola, P. kobayashiana, and P. tesselata), and two new names are introduced [P. kakiigena (≡ Cylindrosporium kaki, non Pseudocercospora kaki), and Zasmidium diospyri-hispidae (≡ Passalora diospyri, non Zasmidium diospyri)]. Six taxa are lectotypified (Cercospora atra, C. diospyri, C. diospyri var. ferruginea, C. flexuosa, C. fuliginosa, C. kaki), and Pseudocercospora kaki is epitypified.

Laser chemical analysis.

Selected applications of laser methods to analytical problems are reviewed. Examples are chosen from multiphoton ionization and laser fluorescence analysis. Although efforts to carry out elemental analysis with laser techniques are probably the most advanced, studies suggest that the analysis of molecular species is also quite promising, particularly in regard to interfacing laser fluorimetric detection with high-performance liquid chromatography. Recent experiments indicate that analysts can expect to attain in a number of cases the ultimate limit of single-atom or single-molecule detection with laser-based methods.

Probing individual molecules with confocal fluorescence microscopy.

Confocal fluorescence microscopy coupled with a diffraction-limited laser beam and a high-efficiency detection system has been used to study the diffusive movement and emission process of individual fluorescent molecules in the liquid phase at room temperature. The high detection sensitivity achieved at fast data acquisition speeds (greater than 1 kilohertz) allows real-time observation of single-molecule fluorescence without statistical analysis. The results show fluorescence-cycle saturation at the single-molecule level and multiple recrossings of a single molecule into and out of the probe volume as well as the triplet state.

Laser fluorimetry: subpicogram detection of aflatoxins using high-pressure liquid chromatography.

The use of high-pressure liquid chromatographic separation in conjunction with laser-induced fluorescence detection permits the analysis of trace fluorescent species at new limits of sensitivity. This technique was applied to the carcinogens aflatoxins B1, B2, G1, and G2, which were linearly quantitated to 7.5 x 10(-13) gram. The procedure consists of forming more fluorescent aflatoxin derivatives, eluting the aflatoxins from a reverse-phase column, focusing the 325-nanometer output of a helium-cadmium ion laser into a suspended droplet of the eluent, and measuring the resulting fluorescence using phase-sensitive detection.

Electrokinetic separation of chiral compounds.

Femtomole amounts of racemic mixtures of derivatized amino acids were resolved and analyzed rapidly in about 10 minutes by means of high-voltage zone electrophoresis with laser-fluorescence detection. The electrophoresis was performed in capillary columns containing a chiral support electrolyte. A number of dansyl amino acids were resolved by the diastereomeric interaction between the DL-amino acid and the copper(II) complex of L-histidine present in the support electrolyte. A combination of electro-osmotic and electrophoretic action caused all species, positively charged, neutral, and negatively charged, to pass through the 0.5- nanoliter detection volume where they were subjected to laser excitation.

Application of two-step laser mass spectrometry to cosmogeochemistry: direct analysis of meteorites.

Polycyclic aromatic hydrocarbons in C1, C2, and C3 carbonaceous chondrites and in some ordinary chondrites have been directly analyzed by two-step laser desorption/ laser multiphoton ionization mass spectrometry, a selective and sensitive method requiring only milligram samples. At the ionization wavelength of 266 nanometers, parent ion peaks of polycyclic aromatic hydrocarbons dominate the mass spectra. Quantitative analysis is possible; as an example, the concentration of phenanthrene in the Murchison meteorite was determined to be 5.0 parts per million.

Capillary electrophoresis.

Electrophoretic separations carried out in capillary tubes offer the possibilities of rapid and automated analyses of small volumes of complex mixtures with unprecedented resolution and sensitivity. Some emerging developments of this new instrumentation are reviewed.

Partial control of an ion-molecule reaction by selection of the internal motion of the polyatomic reagent ion.

The ion-molecule reaction NH(3)(+) + ND(3) has been studied at various collision energies (1 to 5 electron volts in the center of mass) with preparation of the NH(3)(+) reagent in two nearly isoenergetic vibrational states. One state corresponds to pure out-of-plane bending of the planar NH(3)(+) ion (0.60 electron volts), whereas the other state is a combination of in-plane and out-of-plane motion (0.63 electron volts). The product branching ratios differ markedly for these two vibrational-state preparations. The differences in reactivity suggest that the in-plane totally symmetric stretching mode is essentially inactive in controlling the branching ratio of this reaction.

Spatially resolved organic analysis of the allende meteorite.

The distribution of polycyclic aromatic hydrocarbons(PAHs) in the Allende meteorite has been probed with two-step laser desorption/laser multiphoton ionization mass spectrometry. This method allows direct in situ analysis with a spatial resolution of 1 square millimeter or better of selected organic molecules. Spectra from freshly fractured interior surfaces of the meteorite show that PAH concentrations are locally high compared to the average concentrations found by wet chemical analysis of pulverized samples. The data suggest that the PAHs are primarily associated with the fine-grained matrix, where the organic polymer occurs. In addition, highly substituted PAH skeletons were observed. Interiors of individual chondrules were devoid of PAHs at our detection limit(about 0.05 parts per million).

Single cells as biosensors for chemical separations.

A biosensor system based on the response of living cells was demonstrated that can detect specific components of a complex mixture fractionated by a microcolumn separation technique. This system uses ligand-receptor binding and signal-transduction pathways to biochemically amplify the presence of an analyte after electrophoretic separation. The transduced signal was measured by means of two approaches: (i) fluorescence determination of intracellular calcium concentrations in one or more rat PC-12 cells and (ii) measurement of transmembrane current in a Xenopus laevis oocyte microinjected with messenger RNA that encodes a specific receptor. This analysis system has the potential to identify biologically active ligands present in a complex mixture with exceptional sensitivity and selectivity.

Reaction product imaging: the h + d2 reaction.

The differential cross section for the H + D(2) --> HD + D reaction has been measured using a technique called reaction product imaging. In this experiment, a photolytically produced beam of hydrogen (H) atoms crossed a beam of cold deuterium (D(2)) molecules. Product D atoms were ionized at the intersection of the two particle beams and accelerated toward a position-sensitive detector. The ion images appearing on the detector are two-dimensional projections of the three-dimensional velocity distribution of the D atom products. The reaction was studied at nominal center-of-mass collision energies of 0.54 and 1.29 electron volts. At the lower collision energy, the measured differential cross section for D atom production, summed over all final states of the HD(v,J) product, is in good agreement with recent quasi-classical trajectory calculations. At the higher collision energy, the agreement between the theoretical predictions and experimental results is less favorable.

Identification of complex aromatic molecules in individual interplanetary dust particles.

Seventeen stratospherically collected particles-eight of which are classified as interplanetary dust particles (IDPs), seven of which are classified as probable terrestrial contaminants, and two of which have uncertain origins-were studied with a microprobe two-step laser mass spectrometer. Many polycyclic aromatic hydrocarbons(PAHs) and their alkylated derivatives were identified in two of the eight IDPs. The PAHs observed include a high-mass envelope not found in meteorites or terrestrial contaminants and prominent odd-mass peaks suggestive of nitrogen-containing functional groups attached to aromatic chromophores. In addition, the complexity of the IDP mass spectra has no precedence in previous studies of meteorite samples or their acid residues. Extensive checks were performed to demonstrate that the PAH signals are not caused by terrestrial contaminants.

Boundary layer profiles in plasma chemical vapor deposition.

A nonlinear optical spectroscopy based on degenerate four-wave mixing has made possible direct measurements of species temperature and concentration profiles through the boundary layer of a reactive plasma at atmospheric pressure. Spectra were obtained for CH and C(2) radicals over a range of conditions including those for the plasma chemical vapor deposition of diamond films. Numerical simulations based on a one-dimensional stagnation-point flow model are in good agreement with the measurements. The CH mole fraction is shown to rise and fall as a function of distance from the substrate, which is compelling experimental evidence for the complex chemistry that is occurring in the plasma boundary layer.