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"This thesis provides deep insights into currently controversial questions in laser filamentation, a highly complex phenomenon involving nonlinear optical effects and plasma physics. First, based on the concrete picture of a femtosecond laser beam which self-pinches its radial intensity distribution, the thesis delivers a novel explanation for the remarkable and previously unexplained phenomenon of pulse self-compression in filaments. Moreover, the work addresses the impact of a non-adiabatic change of both nonlinearity and dispersion on such an intense femtosecond pulse transiting from a gaseous dielectric material to a solid one. Finally, and probably most importantly, the author presents a simple and highly practical theoretical approach for quantitatively estimating the influence of higher-order nonlinear optical effects in optics. These results shed new light on recent experimental observations, which are still hotly debated and may completely change our understanding of filamentation, causing a paradigm change concerning the role of higher-order nonlinearities in optics."

"Penelitian ini mengeksplorasi katalisis plasmonik, berfokus pada penggunaan resonansi plasmon permukaan terlokalisasi (RPPT) dari nanopartikel untuk mendorong reaksi kimia. Berbeda dengan proses katalitik konvensional, katalisis plasmonik menawarkan sifat unik yang dapat digunakan untuk meningkatkan proses katalitik melalui peningkatan medan elektromagnetik yang diinduksi plasmon, pembentukan muatan (elektron atau hole) berenergi tinggi, atau efek fototermal. Studi numerik menunjukkan bahwa iradiasi laser pulsa dapat lebih efisien untuk katalisis yang diinduksi plasmon dibandingkan dengan laser gelombang kontinu (CW), namun investigasi eksperimental, terutama untuk sintesis nanopartikel bottom-up, masih belum banyak diselidiki. Menggunakan sintesis core-shell Au-Ag sebagai reaksi model, penelitian ini secara eksperimental menyelidiki efek eksitasi laser pulsa nanosekon. Pertama-tama, kami berhasil mensintesis nanopartikel emas (Au) berbentuk bola dengan puncak LSPR yang dapat disesuaikan mendekati panjang gelombang laser 532 nm. Percobaan pemanasan konvensional menunjukkan bahwa pembentukan core-shell terhambat secara kinetik di bawah 55°C. Laser CW (532 nm, 67 mW) tidak memiliki efek signifikan, sedangkan iradiasi laser pulsa nanosekon pada 532 nm secara signifikan menginduksi pembentukan core-shell, dibuktikan dengan pergeseran LSPR ke panjang gelombang lebih pendek yang besar dan peningkatan absorbansi. Laju pertumbuhan shell perak yang tampak meningkat seiring dengan peningkatan daya laser pulsa, menunjukkan pengaruh langsung efek plasmon terhadap kinetika pertumbuhan shell. Temuan ini memberikan pemahaman baru mengenai sintesis nanopartikel yang diinduksi laser pulsa dan potensi laser pulsa untuk meningkatkan proses katalitik secara signifikan dibandingkan metode konvensional lain.

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This study explores plasmonic catalysis, focusing on using localized surface plasmon resonance (LSPR) of nanoparticles to drive chemical reactions. In contrast to conventional catalytic processes, plasmonic catalysis offers unique properties that can be utilized to boost catalytic process via plasmonic-induced electromagnetic field enhancement, hot-carrier generation or photothermal effect. Numerical studies suggest pulsed laser irradiation can be more efficient for plasmon-induced catalysis compared to continuous-wave (CW) lasers, but experimental investigations, particularly for bottom-up nanoparticle synthesis, remain unexplored. Using Au-Ag core-shell synthesis as a model reaction, this research experimentally investigated the effect of nanosecond pulsed laser excitation. We successfully synthesized spherical Au nanoparticles with a tunable LSPR peak near the laser wavelength of 532 nm. Next, conventional heating experiments showed core-shell formation was kinetically inhibited below 55 °C. Crucially, while CW laser (532 nm, 67 mW) had little effect, nanosecond pulsed laser irradiation at 532 nm significantly induced core-shell formation, evidenced by a large LSPR blue shift and increase of absorbance. The apparent silver shell growth rate increased with increasing pulsed laser power, highlighting direct influence of plasmonic-induced effect on shell growth kinetics. These findings highlight the potential of pulsed laser to enhance catalysis significantly in comparison to other methods. "

"The PUILS series delivers up-to-date reviews of progress in Ultrafast Intense Laser Science, a newly emerging interdisciplinary research field spanning atomic and molecular physics, molecular science and optical science which has been stimulated by the recent developments in ultrafast laser technologies. Each volume compiles peer-reviewed articles authored by researchers at the forefront of each their own subfields of UILS. These are followed by reports of cutting-edge discoveries. This eighth volume covers a broad range of topics from this interdisciplinary research field, focusing on molecules interacting with ultrashort and intense laser fields, advanced technologies for the characterization of ultrashort laser pulses and their applications, laser plasma formation and laser acceleration."