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ASML’s extreme ultraviolet (EUV) lithography machines have found widescale adoption in 5 and 3 nm logic nodes and leading-edge DRAM nodes. The tool operates by generating 13.5nm light from a tin plasma source, which is then directed through multiple optics and reflected off the EUV photomask and down to the wafer surface. In the EUV tool, tin and other contaminants are generated, and because no protective pellicle is used in EUV photo-lithography, any contaminate on the EUV photomask will become a defect on the wafer. EUV photomasks therefore need frequent cleaning compared to a traditional photolithography process, which would employ a protective pellicle. Herein, we report on the development of an EUV photomask cleaning solution that was designed to remove Sn, SnO2, and other contaminates from a mask surface without damaging the mask’s tantalum absorber and ruthenium capping layers. Our mask cleaning solution extends photomask lifetime and can improve operational performance and quality control.

In the photolithographic process of semiconductor manufacture, a photoresist is exposed to light and then developed to create a pattern on the photoresist surface. After development, a rinse step is necessary to prevent pattern collapse and to remove polymer residues that linger after development. Surfactants are essential in these rinse solutions and help mobilize polymer residues while also minimizing capillary forces that are responsible for pattern collapse. An ideal surfactant system interacts with the polymer surface enough to mobilize debris particles, but not enough to cause swelling and shift the critical dimension; while at the same time creating a surface tension and contact angle to prevent pattern collapse. In this work, we investigated various non-fluorinated surfactants and their interaction with EUV photoresists by measuring surface tension, contact angle, and photoresist swelling. Although the difference of solubility parameters (DSP) between surfactants and photoresists were shown to correlate to photoresist swelling. No correlation between resist swelling and the difference of solubility parameters was found in the study. Through this work, we identified that ideal surfactant rinse properties can be achieved in a fluoro-free surfactant formulation. Ideal fluoro-free EUV surfactant rinse formulations achieve no pattern collapse, low CD-shift, and good residue clean performance for an EUV photolithographic process.

The reaction of methyl anthranilates with N-arylcyanamides in the presence of p-TsOH in t-BuOH under reflux afforded predominantly 3-arylquinazolin-4-ones. In contrast, the reaction of the same reactants with TMSCl in t-BuOH at 60 °C followed by the Dimroth rearrangement in aqueous ethanolic sodium hydroxide gave exclusively the regioisomers, 2-(N-arylamino)quinazolin-4-ones. The regioselective synthesis of N-aryl-substituted 2-aminoquinazolin-4-ones can be further applied to the synthesis of benzimidazo[2,1-b]quinazolin-12-ones.

A facile and general synthesis of various N-substituted cyanamides was accomplished by the Tiemann rearrangement of amidoximes with benzenesulfonyl chlorides (TsCl or o-NsCl) and DIPEA.

CuI-Catalyzed intramolecular aminocyanation of terminal alkynes in N-(2-ethynylphenyl)-N-sulfonylcyanamides was initiated by the formation of Cu–acetylide to trigger N–CN bond cleavage of the N-sulfonylcyanamide moiety followed by CN migration to form a β-cyano Cu–vinylidene intermediate. Subsequently, the indole ring closure furnished the corresponding 1-sulfonyl-3-cyanoindoles.

The regulation of light-harvesting in photosynthesis under conditions of varying solar light irradiation is essential for the survival and fitness of plants and algae. It has been proposed that rearrangements of protein distribution in the stacked grana region of thylakoid membranes connected to changes in the electronic pigment-interaction play a key role for this regulation. In particular, carotenoid−chlorophyll interactions seem to be crucial for the down- regulation of photosynthetic light-harvesting. So far, it has been difficult to determine the influence of the dense protein packing found in native photosynthetic membrane on these interactions. We investigated the changes of the electronic couplings between carotenoids and chlorophylls and the quenching in grana thylakoids of varying protein packing density by two-photon spectroscopy, conventional chlorophyll fluorometry, low-temperature fluorescence spectroscopy, and electron micrographs of freeze-fracture membranes. We observed an increasing carotenoid−chlorophyll coupling and fluorescence quenching with increasing packing density. Simultaneously, the antennas size and excitonic connectivity of Photosystem II increased with increasing quenching and carotenoid−chlorophyll coupling whereas isolated, decoupled LHCII trimers decreased. Two distinct quenching data regimes could be identified that show up at different protein packing densities. In the regime corresponding to higher protein packing densities, quenching is strongly correlated to carotenoid−chlorophyll interactions whereas in the second regime, a weak correlation is apparent with low protein packing densities. Native membranes are in the strong-coupling data regime. Consequently, PSII and LHCII in grana membranes of plants are already quenched by protein crowding. We concluded that this ensures efficient electronic connection of all pigment−protein complexes for intermolecular energy transfer to the reaction centers and allows simultaneously sensitive regulation of light harvesting by only small changes in the protein packaging.

Recently, excitonic carotenoid-chlorophyll interactions have been proposed as a simple but effective model for the down-regulation of photosynthesis in plants. The model was proposed on the basis of quenching-correlated electronic carotenoid-chlorophyll interactions (Car S(1) → Chl) determined by Car S(1) two-photon excitation and red-shifted absorption bands. However, if excitonic interactions are indeed responsible for this effect, a simultaneous correlation of quenching with increased energy transfer in the opposite direction, Chl Q(y) → Car S(1), should be observed. Here we present a systematic study on the correlation of Car S(1) → Chl and Chl → Car S(1) energy transfer with the occurrence of red-shifted bands and quenching in isolated LHCII. We found a direct correlation between all four phenomena, supporting our conclusion that excitonic Car S(1)-Chl interactions provide low-lying states serving as energy traps and dissipative valves for excess excitation energy.

The aggregation dependent correlation between fluorescence quenching and the electronic carotenoid–chlorophyll interactions, ϕ Coupling Car S 1 - Chl , as measured by comparing chlorophyll fluorescence observed after two- and one-photon excitation, has been investigated using native LHC II samples as well as mutants lacking Chl 2 and Chl 13. For native LHC II the same linear correlation between ϕ Coupling Car S 1 - Chl and the fluorescence quenching was observed as previously reported for the pH and Zea-dependent quenching of LHC II [1] . In order to elucidate which carotenoid–chlorophyll pair might dominate this correlation we also investigated the mutants lacking Chl 2 and Chl 13. However, also with these mutants the same linear correlation as for native LHC II was observed. This provides indication that these two chlorophylls play only a minor role for the observed effects. Nevertheless, we also conclude that this does not exclude that their neighboured carotenoids, lutein 1 and neoxanthin, might interact electronically with other chlorophylls close by.

This study compared the antinociceptive and anti-inflammatory effects of various parts of Broussonetia papyrifera (L.) L'Herit. ex Vent. (BP, Moraceae) by chemical-induced pain and inflammation in rodents. All BP parts (1 and 2 g/kg, p.o.) effectively inhibited writhing responses induced by 1% acetic acid. The BP radix, leaf, and fruit effectively inhibited the late-phase licking responses caused by 1% formalin. But only the BP radix and fruit reduced the edema induced by 1% carrageenan at 1-2 h. Furthermore, the BP radix reduced the abdominal Evan's blue extravasations caused by inflammatory mediators, including serotonin and sodium nitroprusside. Finally, the radix had the highest contents of betulin and betulinic acid among all BP parts. In conclusion, the radix is the better medicinal BP part possessing antinociceptive and antiinflammatory effects, and its anti-inflammatory effects are partially related to the inhibition of vascular permeability via autocrines and nitric oxide.

The Car S 1 → Chl energy transfer efficiency, Φ Transfer , in xanthophyll-cycle mutants of living plants and LHC II was investigated by selective Car S 1 two-photon excitation. Before high-light illumination Φ Transfer , of the violaxanthin deficient mutant npq2 is ∼30% smaller than the corresponding value for wild type plants. For the zeaxanthin deficient mutant, npq1, Φ Transfer is ∼30% larger. Wild type Arabidopsis thaliana is the only variant which is capable of a light-dependent decrease of up to 40% and complete recovery to the original Φ Transfer values. In contrast, Φ Transfer remains constant during dark adaptation in both mutants. Surprisingly, changes in Φ Transfer of LHC II preparations were less than 5% only, when substituting violaxanthin by zeaxanthin.

It is known that aggregation of isolated light-harvesting complex II (LHCII) in solution results in high fluorescence quenching, reduced chlorophyll fluorescence lifetime, and increased electronic coupling of carotenoid (Car) S-1 and chlorophyll (Chl) Q(y) states, as determined by two-photon studies. It has been suggested that this behavior of aggregated LHCII mimics aspects of non-photochemical quenching processes of higher plants and algae. However, several studies proposed that the minor photosystem II proteins CP24 and CP29 also play a significant role in regulation of photosynthesis. Therefore, we use a simple protocol that allows gradual aggregation also of CP24 and CP29. Similarly, as observed for LHCII, aggregation of CP24 and CP29 also leads to increasing fluorescence quenching and increasing electronic Car S-1-Chl Q(y) coupling. Furthermore, a direct comparison of the three proteins revealed a significant higher electronic coupling in the two minor proteins already in the absence of any aggregation. These differences become even more prominent upon aggregation. A red-shift of the Q(y) absorption band known from LHCII aggregation was also observed for CP29 but not for CP24. We discuss possible implications of these results for the role of CP24 and CP29 as potential valves for excess excitation energy in the regulation of photosynthetic light harvesting.

Fifty-six volatile organic compounds (VOCs), known to be ozone precursors, were stored in three media (SUMMA and Silocan canisters and Tedlar bags) to evaluate their stability in these storage media. An analysis of samples of air followed the procedures described in the US EPA Method TO-15, and was performed using gas chromatograph (GC) equipped with a mass spectrometer (MS). The first-order decay model matched 87 % of the observations. These 56 VOCs were classified into four groups-alkanes, alkenes, aromatics and biogenics. Alkenes and biogenics exhibited lower recovery rates than those of alkanes and aromatics. After a seven-day (7-d) storage period, 87 % of alkenes could be recovered from canister storage and 82 % were recovered from Tedlar bag storage. Isoprene, a major component in biogenic VOCs, exhibited a recovery rate of only 75±8 % after storage for seven days in canisters and Tedlar bags. Storage conditions (humidity and temperature) affected the degradation constant of each VOC. The calculated average half-lifes of 56 VOCs for SUMMA canisters, Silcocan canisters, and Tedlar bags were 45±6, 52±6, and 37±4 days, respectively. The VOCs stored in Tedlar bags had a lower recovery than those stored in canisters.

A facile and general synthesis of various N-substituted cyanamides was accomplished by the Tiemann rearrangement of amidoximes with benzenesulfonyl chlorides (TsCl or o-NsCl) and DIPEA.

The photosystem II (PSII) subunit S (PsbS) plays a key role in nonphotochemical quenching, a photoprotective mechanism for dissipation of excess excitation energy in plants. The precise function of PsbS in nonphotochemical quenching is unknown. By reconstituting PsbS together with the major light-harvesting complex of PSII (LHC-II) and the xanthophyll zeaxanthin (Zea) into proteoliposomes, we have tested the individual contributions of PSII complexes and Zea to chlorophyll (Chl) fluorescence quenching in a membrane environment. We demonstrate that PsbS is stable in the absence of pigments in vitro. Significant Chl fluorescence quenching of reconstituted LHC-II was observed in the presence of PsbS and Zea, although neither Zea nor PsbS alone was sufficient to induce the same quenching. Coreconstitution with PsbS resulted in the formation of LHC-II/PsbS heterodimers, indicating their direct interaction in the lipid bilayer. Two-photon excitation measurements on liposomes containing LHC-II, PsbS, and Zea showed an increase of electronic interactions between carotenoid S 1 and Chl states, , that correlated directly with Chl fluorescence quenching. These findings are in agreement with a carotenoid-dependent Chl fluorescence quenching by direct interactions of LHCs of PSII with PsbS monomers.

In two recent studies, energy transfer was reported in certain phthalocyanine-carotenoid dyads between the optically forbidden first excited state of carotenoids (Car S(1)) and phthalocyanines (Pcs) in the direction Pc → Car S(1) (Kloz et al., J Am Chem Soc 133:7007-7015, 2011) as well as in the direction Car S(1) → Pc (Liao et al., J Phys Chem A 115:4082-4091, 2011). In this article, we show that the extent of this energy transfer in both directions is closely correlated in these dyads. This correlation and the additional observation that Car S(1) is instantaneously populated after Pc excitation provides evidence that in these compounds excitonic interactions can occur. Besides pure energy transfer and electron transfer, this is the third type of tetrapyrrole-carotenoid interaction that has been shown to occur in these model compounds and that has previously been proposed as a photosynthetic regulation mechanism. We discuss the implications of these models for photosynthetic regulation. The findings are also discussed in the context of a model in which both electronic states are disordered and in which the strength of the electronic coupling determines whether energy transfer, excitonic coupling, or electron transfer occurs.

Electronic interactions between the first excited states (S(1)) of carotenoids (Car) of different conjugation lengths (8-11 double bonds) and phthalocyanines (Pc) in different Car-Pc dyad molecules were investigated by two-photon spectroscopy and compared with Car S(1)-chlorophyll (Chl) interactions in photosynthetic light harvesting complexes (LHCs). The observation of Chl/Pc fluorescence after selective two-photon excitation of the Car S(1) state allowed sensitive monitoring of the flow of energy between Car S(1) and Pc or Chl. It is found that two-photon excitation excites to about 80% to 100% exclusively the carotenoid state Car S(1) and that only a small fraction of direct tetrapyrrole two-photon excitation occurs. Amide-linked Car-Pc dyads in tetrahydrofuran demonstrate a molecular gear shift mechanism in that effective Car S(1) → Pc energy transfer is observed in a dyad with 9 double bonds in the carotenoid, whereas in similar dyads with 11 double bonds in the carotenoid, the Pc fluorescence is strongly quenched by Pc → Car S(1) energy transfer. In phenylamino-linked Car-Pc dyads in toluene extremely large electronic interactions between the Car S(1) state and Pc were observed, particularly in the case of a dyad in which the carotenoid contained 10 double bonds. This observation together with previous findings in the same system provides strong evidence for excitonic Car S(1)-Pc Q(y) interactions. Very similar results were observed with photosynthetic LHC II complexes in the past, supporting an important role of such interactions in photosynthetic down-regulation.

Nonphotochemical quenching (NPQ) is the fundamental process by which plants exposed to high light intensities dissipate the potentially harmful excess energy as heat. Recently, it has been shown that efficient energy dissipation can be induced in the major light-harvesting complexes of photosystem II (LHCII) in the absence of protein-protein interactions. Spectroscopic measurements on these samples (LHCII gels) in the quenched state revealed specific alterations in the absorption and circular dichroism bands assigned to neoxanthin and lutein 1 molecules. In this work, we investigate the changes in conformation of the pigments involved in NPQ using resonance Raman spectroscopy. By selective excitation we show that, as well as the twisting of neoxanthin that has been reported previously, the lutein 1 pigment also undergoes a significant change in conformation when LHCII switches to the energy dissipative state. Selective two-photon excitation of carotenoid (Car) dark states (Car S(1)) performed on LHCII gels shows that the extent of electronic interactions between Car S(1) and chlorophyll states correlates linearly with chlorophyll fluorescence quenching, as observed previously for isolated LHCII (aggregated versus trimeric) and whole plants (with versus without NPQ).

Selective 2-photon excitation (TPE) of carotenoid dark states, Car S 1 , shows that in the major light-harvesting complex of photosystem II (LHCII), the extent of electronic interactions between carotenoid dark states (Car S 1 ) and chlorophyll (Chl) states, φ Coupling Car S 1 −Chl , correlates linearly with chlorophyll fluorescence quenching under different experimental conditions. Simultaneously, a linear correlation between both Chl fluorescence quenching and φ Coupling Car S 1 −Chl with the intensity of red-shifted bands in the Chl Q y and carotenoid absorption was also observed. These results suggest quenching excitonic Car S 1 −Chl states as origin for the observed effects. Furthermore, real time measurements of the light-dependent down- and up-regulation of the photosynthetic activity and φ Coupling Car S 1 −Chl in wild-type and mutant ( npq1 , npq2 , npq4 , lut2 and WT + PsbS ) Arabidopsis thaliana plants reveal that also in vivo the quenching parameter NPQ correlates always linearly with the extent of electronic Car S 1 –Chl interactions in any adaptation status. Our in vivo measurements with Arabidopsis variants show that during high light illumination, φ Coupling Car S 1 −Chl depends on the presence of PsbS and zeaxanthin (Zea) in an almost identical way as NPQ. In summary, these results provide clear evidence for a very close link between electronic Car S 1 –Chl interactions and the regulation of photosynthesis. These findings support a photophysical mechanism in which short-living, low excitonic carotenoid–chlorophyll states serve as traps and dissipation valves for excess excitation energy.