Every macroscopic chemical transformation, whether it is atmospheric ozone depletion or the burning of a candle, consists of millions of microscopic chemical events which involve collisions between molecules. It has been the dream of scientists for a long time to observe and understand the details of molecular collisions which transform reactant molecules into product molecules with our naked eyes. During the last several decades, because of the advances in crossed molecular beams method and laser technology, especially, from the measurements of product angular and velocity distributions, it has become possible to “visualize” exact details of how chemical reactions take place through molecular collisions or through photochemical processes.
Whether two reactant molecules can transform into product molecules during collisional processes depends not only on the orientations of molecules when they approach each other, but also on the energy contents of reactant molecules. Reactants must contain sufficient energy to overcome potential energy barriers on their way to product formation. However, when a molecule is energized, there are many different modes in which the required energy could be deposited. Whether the energy is in the translational, the rotational, the vibrational, or the electronic degrees of freedom will have different effects in promoting chemical reactions.
In this lecture, in addition to illustrate experimental details of crossed molecular beams method, examples will be given to demonstrate how detail information on the dynamics of chemical reactions and photochemical processes can be obtained using various experimental approaches.
無論是臭氧層的破壞或是蠟燭的燃燒，每一個巨觀的化學轉換，都包含了數以百萬計由分子碰撞所構成的微觀化學事件。科學家長久以來的夢想，就是能用自己的眼睛來觀察並了解這些使反應物轉換成產物的分子碰撞之詳細情形。數十年來，因為交叉分子束方法與雷射技術的進步，尤其是得以量測產物的角度與速度分佈，使得“眼見”化學反應過程中的確切細節成為可能，這些化學反應可以來自於分子的碰撞或是光化學的過程。
在此演講中，除了描述分子束的實驗外，也會包括我個人沉浸於化學反應動態學領域四十年來的經驗。
大師演講：Challenges of Human Society in the 21st Century
二十一世紀人類社會的挑戰
During the long history of mankind, the planet of earth used to be an infinitely large place. But after the industrial revolution and especially during the twentieth century things have changed dramatically. World population increased from 1.5 billion to 6 billion and the earth has shrunk in relative terms. This sudden transition from “unlimited earth” to “limited earth” has extremely significant consequences, yet the development of human society, moving along the track of infinity for a long time, has not seemed to be able to adapt to the new reality that the earth is “limited.”
On the “limited earth,” perhaps the most important challenges for scientists are problems related to the use of energy and the impact on our living environment. The “developed” countries’ patterns of growth obviously are not the ideal models for “not yet overdeveloped” countries to emulate. We need to find a new, sustainable way of development for entire human society on earth, paying special attention to harmonizing the relationship between humankind and nature.
We should all recognize the fact that the increasingly interconnected world cannot be a safe place if a large portion of its population still suffers from poverty, diseases, illiteracy, unemployment, and other barriers to survival. Scientists can play key roles in finding the solutions to these problems. Especially, if we learn to solve problems together, learn to share knowledge, new technological options and the limited resources available, learn to respect and understand different cultural heritages, then it will be possible to realize the establishment of a genuine global village that enables sustainable development for all.
This is the first time in human history that all human beings on earth have been faced with learning to work together and live together as one family in a global village. Our future depends entirely on how effectively the entire world would function as a community. This is a necessary awakening – vital for the survival and sustainable development of mankind.
在人類的漫長歷史過程中，地球一直被視為是無限大。但是在工業革命後，特別是在二十世紀時，看法有很大的轉變。世界人口從15億人增加到60億人，地球上的活動空間已相對地縮小了。從「無限的地球」急轉至「有限的地球」衍生出極具意義的結果：人類社會的發展，長久以來秉持「無限」的思維，已經不能適應新的現實—地球是有限的。
就有限的地球而論，對科學家們的最重大挑戰，或許是涉及能源使用和其對生活環境衝擊的問題。「已發展國家」的成長方式，顯然不是「尚未發展國家」所應仿效的理想模式。我們需要為地球上的全體人類社會，尋找出一種新的，能永續發展的方式，特別是兼顧到人類和自然界之間的和諧共存。
我們都應該承認這一事實：如果有一大部分的人口困於貧窮、疾病、文盲、失業、和其他生存障礙，那麼這個日漸交互連結的世界不會是安全的處所。為解決這些問題，科學家們可以擔任主要的角色。尤其是若我們學會如何共同解決問題；學會分享知識、新科技和有限的資源；學會尊重和了解不同的文化傳承，則一個可以為全體人類社會永續發展的真正地球村，是有可能實現的。
這是人類歷史上的第一次：地球上的所有人，面對如何學習一起工作和共同生活，如同地球村的一家人。我們的未來完全決定於，整個世界如何有效地運作如同一個社區。這是一個必要的警醒—攸關人類的生存和永續發展。 |
