Fluorine—an enabler in advanced photolithography

Fluorine—its chemical and physical properties—plays a critical role in the development of advanced photolithography. It is widely expected that, when in a few years the critical dimensions in microelectronic devices will be less than ∼70 nm, the patterning technology of choice will be based on 157 nm light generated from molecular fluorine laser medium. Lithography at 157 nm also requires major advances in areas of fluorine science, from the growth of near-perfect calcium fluoride crystals for lenses to fluorine doping of fused silica for masks to the synthesis of fluoropolymers that would serve as pellicles, photoresists, and immersion liquids. With the expected resolution of these issues, the prospects are excellent that photolithography will continue as the main semiconductor patterning technology for at least another decade.     

Vibrational dynamics of some anions in aqueous solutions from isotropic Raman scattering

From the I_VV and I_VH Raman spectra of a totally symmetric vibration, isotropic scattering profiles have been obtained for several anions in dilute aqueous solutions at various temperatures. The Raman spectrometer was connected to an A/D converter and a small computer, which allowed multiple scanning, data accumulation, and numerical processing of these profiles with good precision over a frequency range of about 20 times their full width at half peak height.The theoretical analysis of the isotropic Raman profiles was accomplished by assuming vibrational phase relaxation based on a MARKOV-GAUSS mechanism. Fitting procedures to the experimental data permitted the determination of the vibrational frequency distribution and its modulation time. Temperature effects are discussed in relation to the distribution and motional characteristics of the immediate environment of water molecules of the anions.     

Infrared dephasing of degenerate fundamentals: The ν6 mode of liquid CD3I

A model of vibrational dephasing with motional narrowing by the librational motions of the molecules in their cages is tested on the example of the ν₆ degenerate infrared fundamental of liquid CD₃l at room temperature.     

Determination of gamma-hydroxybutyric acid in serum and urine by headspace solid-phase dynamic extraction combined with gas chromatography–positive chemical ionization mass spectrometry

Gamma-hydroxybutyric acid is an emerging drug of abuse. Beside relaxation and euphoria it causes hypnosis and unconsciousness. Therefore the substance is misused as recreational drug and at drug-facilitated sexual assaults. An automated and effortless method for quantitation of gamma-hydroxybutyric acid in serum and urine was optimized and validated. Five hundred microliters sample volume are used for both matrices. The acid catalyzed conversion of gamma-hydroxybutyric acid to the corresponding gamma-butyrolactone is applied. Furthermore the method is based on headspace solid-phase dynamic extraction coupled with gas chromatography–mass spectrometry. The extraction process is performed by repeated aspiration and ejection of the headspace through a steel cannula which is coated on the inside with a polydimethylsiloxane sorbent. Thus absorption of analyte molecules by the sorbent is achieved. The influence of parameters as sorbent type, incubation temperature, number of extraction strokes, injection port temperature and injection flow speed on extraction recovery was investigated. The validation revealed good accuracy with a bias less than ±5%. Intra- and interday precision determined at 10, 50 and 150 μg/ml for each matrix were in following ranges: 1.96–3.49% (intraday, serum), 2.38–4.31% (intraday, urine), 2.33–5.13% (interday, serum) and 2.53–5.64% (interday, urine). The method provided good linearity between 2 and 200 μg/ml yielding coefficients of determination R² ≥ 0.9985. Limit of detection were determined at 0.16 μg/ml for serum and 0.17 μg/ml for urine, respectively. This method exhibits a fast, solvent-free and widely automated extraction process. It has been applied to toxicological routine analysis and therapeutic drug monitoring successfully.     

Periodically poled BaMgF(4) for ultraviolet frequency generation

Ferroelectric domain inversion has been demonstrated in BaMgF(4) . Transparency has been measured to <140nm, and no change in transmission was measured under 157-nm irradiation for >1.1x10(9) shots at 2mJ/cm(2) per pulse. First-order quasi-phase-matched generation of 157 nm is predicted by use of grating periods as long as 1.5mum. This material should permit shorter-wavelength chi((2)) frequency-mixing processes than with any other crystalline material.