瞬態吸收光譜學 (transient absorption spectroscopy, TAS) 為結合光學及化學的跨領域研究。可藉由觀察材料中的電子隨時間演變的過程，再經由光學及化學相關的分析，得到材料的電子遷移率等等的資訊。而用高重複率量測有許多好處，不僅可以提升訊號的信噪比，並可以大幅縮短量測的時間。而本篇文章中使用Prof. Pi-Tai Chou(周必泰)’s group 提供的[Pt(py-fpm)2] (4H) 演示我們的瞬態吸收光譜系統時間解析的能力。[Pt(py-fpm)2] (4H)是一個在近紅外光波段具有良好的發光效率的新穎材料，為了要更全貌的了解 [Pt(py-fpm)2] (4H)，我們對它作一系列的瞬態吸收光譜的量測。
我們使用了摻鐿光纖雷射放大器為初始雷射，提供的脈衝寬度為190 fs、脈衝能量為800 μJ、重複率為3.125 kHz。透過重複路徑多重薄片展頻技術(DPMPC)展頻及壓縮後，可以得到約5 fs、147 μJ的泵浦(pump)與偵測(probe)脈衝。而probe脈衝在透過線性位移平台改變與pump脈衝之間的時間延遲後，量測出瞬態吸收光譜圖。我們發現 [Pt(py-fpm)2] (4H) 具有33〖 cm〗^(-1) 的緩慢振動，驗證了此材料打破能係定律(energy gap law)的原因。除此之外，我們也觀察了pump以不同的脈衝寬度及不同的激發波長對其吸收光譜的影響，由此驗證瞬態吸收光譜學量測上時間解析度的重要性。

Transient absorption spectroscopy (TAS) produced by a combination of optics and chemistry. Observe the kinetic of electrons in the material, and then obtain information such as the mobility of the material through optical and chemical analysis. TAS measurement with high repetition rate has some advantages, not only can improve the signal-to-noise ratio of the signal, but also can greatly shorten the measurement required time. The [Pt(py-fpm)2] (4H), which provide by Prof. Pi-Tai Chou(周必泰)’s group, is used to demonstrate the time-resolving capability of our TAS system. This material has good luminous efficiency in the near-infrared light region. In order to understand [Pt(py-fpm)2] (4H) more comprehensively, we make a series of transient absorption spectroscopic experiments on it.
We use a ytterbium-doped fiber laser amplifier as the initial light source, and the input pulse duration is 190 fs, the pulse energy is 800 μJ, and the repetition rate is 3.125 kHz. After double-pass multiple-plate continuum (DPMPC) broadens the spectrum and pulse compression, the pump and probe both have about 5 fs, 147 μJ pulses. The probe changes the delay between the pump and the probe through a linear translation stage and measures the transient absorption spectrum. We found that [Pt(py-fpm)2] (4H) has slow vibration of 33〖 cm〗^(-1), verifying the reason why this material breaks the energy gap law. In addition, we also observed the effect of the pump with different pulse duration and different excitation wavelengths on its transient absorption spectrum, thus proving the importance of time resolution in TAS measurement.

摘要.....i
Abstract.....ii
Table of contents.....iv
Acknowledgment.....v
List of figures and tables.....vi
Chapter 1. Introduction.....1
Chapter 2. Theory.....5
2.1 Spectral broadening mechanisms.....5
2.1.1 Optical Kerr effect and self-focusing.....6
2.1.2 Self-phase modulation.....8
2.1.3 Self-steepening.....13
2.1.4 Multiple-plate continuum technique.....14
2.2 Dispersion compensation.....16
2.3 Pulse measurement.....19
2.4 Transient absorption spectroscopy system.....25
2.4.1 Normalized differential transmission spectrum (ΔT/T) definition.....25
2.4.2 Single-shot transient absorption spectroscopy measurement.....27
2.4.3 Interpretation of the signal from TA.....29
2.5 Noise contributions.....31
Chapter 3. Experiment.....34
3.1 Material characteristic.....34
3.2 Experiment setup.....37
3.3 Transient absorption spectroscopy results.....39
Chapter 4. Conclusion and future works.....53
References.....56
Appendix A. Polarization-gating frequency-resolved optical gating results.....59

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