Pavel Matousek

Prospects for the diagnosis of breast cancer by noninvasive probing of calcifications using transmission Raman spectroscopy

Breast calcifications can be found in both benign and malignant lesions, and the composition of these calcifications can indicate the possible disease state. As current practices such as mammography and histopathology examine the morphology of the specimen, they cannot reliably distinguish between the two types of calcification, which frequently are the only mammographic features that indicate the presence of a cancerous lesion. Raman spectroscopy is an optical technique capable of obtaining biochemical information of a sample in situ. We demonstrate for the first time the noninvasive recovery of Raman spectra of calcified materials buried within a chicken breast tissue slab 16 mm thick, achieved using transmission Raman spectroscopy. The spectra of both calcium hydroxyapatite (HAP) and calcium oxalate monohydrate (COM) are obtained and chemically identified. The experimental geometry and gross insensitivity of the Raman signal to the depth of the calcified lesion makes the concept potentially well suited for probing human female breasts, in conjunction with existing mammography or ultrasound, to provide complementary data in the early diagnosis of breast cancer.

Evaluation of an ultrabroadband high-gain amplification technique for chirped pulse amplification facilities

Recently, an amplification technique for ultrashort pulses was explored in detail in a theoretical paper by Ross et al. [Opt. Commun. 144, 125 (1997)]. The technique, based on nonlinear optics, is called optical parametric chirped pulse amplification. It has a number of features that, in principle, make it highly attractive. It primarily offers extremely large gains simultaneously with extremely large bandwidths. Additional attractions are virtually no spatial and temporal phase distortion of the amplified pulse, high efficiencies and a low thermal loading, reduced amplified spontaneous emission levels, small optical material lengths, and an inherent simplicity of implementation. We present an evaluation of the technique as a front end amplifier for the ultrashort pulse amplification chain of the Vulcan laser system. Such a device could replace some of the existing amplification in Nd:glass and additionally have a wider effect as a direct replacement of Ti:sapphire regenerative amplifiers on large-scale chirped pulse amplification scale facilities.

Photoelectron spectroscopy of S1 toluene: II. Intramolecular dynamics of selected vibrational levels in S1 toluene studied by nanosecond and picosecond time-resolved photoelectron spectroscopies

We present results which suggest that the photophysics of S(1) toluene is significantly more complicated than that of the related molecules p-fluorotoluene or p-difluorobenzene. We have measured a range of photoelectron spectra for a number of S(1) internal energies, on different time scales and at different temperatures, in an attempt to unravel the competing processes, but the final conclusion remains outstanding.

Development of a Novel Large Bandwidth Front-End System for High Peak Power OPCPA Systems

We present the development of a novel large bandwidth front-end that is capable of supporting sub 30fs pulses, with 1J of energy at a 2Hz repetition rate that is centred at 910nm.

A photophysical study of substituted arylethynylenes

A study of a group of compounds based on the 1,4-bis(phenylethynyl)benzene (1) architecture was undertaken to improve our understanding of their photophysics and the factors which control their geometry and hence the π- conjugation pathway in the ground and excited state of these compounds. 1 exists as a range of molecular rotamers in the ground state, resulting from the low barrier to rotation around their C(sp)-C(sp2) bonds. These compounds are highly conjugated systems with good electron conducting properties, due to delocalisation of the HOMO and LUMO over the molecule. In the electronic excited state they are capable changing their molecular conformation and will adopt a planar, or near planar, low energy conformation prior to fluorescence emission in solution. In a glassy matrix at 77 K with sterically hindering substituents on the benzene rings of 1, emission form high and low energy conformations are observed. 1 is highly emissive owing to the high oscillator strength of the S1→S0 transition. All the compounds studied maintained their C≡C character in the excited singlet and triplet states. The substitution of the central benzene ring in 1 with a thiophene moiety increases the singlet oxygen generation quantum yield, which is consistent with greater intersystem crossing to the triplet excited state.